Engineering

Publication Search Results

Now showing 1 - 10 of 52
  • (1995) Mubaraki, Brian; Bandyopadhyay, Srikanta; Fowle, R; Mathew, Philip; Heath, P
    Journal Article

  • (2008) Wakefield, Claire; Meiser, Bettina; Gaff, C; Barratt, Anthony; Patel, Minoo; Suthers, G; Lobb, Elizabeth; Ramsay, J; Mann, G
    Journal Article
    Purpose: Despite the established importance of the role of family history in prostate cancer, relatively little research encompasses the psychosocial issues relevant to unaffected men with a family history of prostate cancer. To determine the completeness and quality of available literature on the issues faced by men with a high risk of prostate cancer, we conducted a multidisciplinary review of the literature to provide some guidance on the information that clinicians might provide to men who are concerned about family history. Materials and Methods: A structured literature search was conducted by a multidisciplinary team of clinicians and researchers who reviewed the medical and psychosocial literature, and identified 21 relevant studies. Results: Research suggests that many high risk patients are concerned about the risk of prostate cancer, and some may significantly overestimate that risk. Several studies have shown high screening rates among high risk patients and high levels of interest in genetic testing for prostate cancer risk should it become available, yet many men also report a desire for more information about their personal risk and risk management options. Conclusions: Given the lack of clear data on the efficacy of prostate cancer screening among high risk patients, clinicians could consider providing men who are concerned about family history with information on their personal risk, help them to clarify the potential benefits, limitations and harms of prostate cancer screening in their situation, and then support their choice regarding the management of prostate cancer risk.

  • (2001) Helmore, Phillip
    Journal Article
    The March 2001 issue of MARENSA’s newsletter, Seaspace, carried the following report: ‘It is understood that HMAS Brisbane and HMAS Anzac competed recently in a sharp sprint over a three-mile course. Anzac had hoped that a quick engagement of gas turbine power would get them first to the finish line, but Brisbane’s 35-year-old boilers and steam turbines responded promptly to full throttle and the old girl showed she still had an unequalled turn of speed. It has been reported that she reached 32 knots on one minute from a standing start.’ Having no experience with the acceleration of naval vessels, reaching 32 knots in one minute from a standing start sounded very quick to me. With interest aroused, I pulled out my copy of Lackenby’s (1952) paper and did the following calculations to check whether the claim was reasonable:

  • (1998) Helmore, Phillip
    Journal Article
    A recent publication says that the primary spelling of the word for the depth of water required to float a ship is draught, with draft as the secondary spelling. A survey of thirty practising naval architects was made to check the claim, and found that a large majority of Australian-educated naval architects spell it draft. The overall results are interesting and are given here.

  • (1998) Helmore, Phillip
    Journal Article
    The two types of marine hydrometer commonly used by naval architects and surveyors measure two distinct, but related, properties. The properties have different units and are used for different purposes. Some users may not be aware of the two types of hydrometer, the properties measured, or the errors which can significantly affect the end result. The relationships between the measured properties are discussed, together with the specific applications of the two types of hydrometer. The conversion of measurements made on one type of hydrometer to the other type is given, with examples of the conversions. Application of the principles presented here will prevent confusion and ensure the use, rather than abuse, of the two types of marine hydrometer.

  • (2001) Doctors, Lawrence; Helmore, Phillip; Loadman, Dougal; Robards, Simon William
    Journal Article
    The influence of fore-and-aft asymmetry of a ship is known to be ignored in the classic thin-ship theory for resistance. In the current work, a more sophisticated approach is utilized in which the sinkage and trim are accounted for within the framework of the same theory. It is shown that the enhanced computer program correctly predicts that vessels with the centre of buoyancy forward of midships suffer a greater sinkage. In addition, the trim is relatively more by the bow. Finally, it is demonstrated that the inclusion of the effects of sinkage and trim in the analysis results in a slightly increased resistance for vessels with the centre of buoyancy forward of midships, in keeping with the experimental evidence.

  • (2008) Ng, Lawrence; Zarrabi, Khosrow
    Journal Article
    Abstract This paper demonstrates the application of a new multiaxial creep damage model developed by the authors to predict the failure time of components made of service aged 2.25%Cr-1%Mo, 0.5%Cr-0.5%Mo-0.25%V low alloy steels, titanium and nickel-based superalloys. The model accounts for the tertiary creep behaviour and assumes the creep damage is related to the internal energy absorbed by the material. The authors argue that the model is the most appropriate for characterizing gross creep damage from a macroscopic point of view because it takes into accounts both the multiaxial internal deformation and loading. The verification and application of the model are demonstrated by applying it to the Bridgman notched bars for which the experimental data are available. The predicted failure times by the model are compared with the experimental results and those obtained from the reference stress method. The results show that the proposed model is capable of predicting failure times of the components made of the above-mentioned materials with an accuracy of 2.2% or better. Also, it is shown that the model predicts the creep failure times of the components more accurately than the reference stress method.

  • (2008) Zarrabi, Khosrow; Basu, Abheek
    Journal Article
    Abstract. Boilers in power, refinery and chemical processing plants contain extensive range of tube bends. Tube bends are manufactured by bending a straight-section tube. As a result, the cross-section of a tube bend becomes oval. Using the finite element analysis (FEA) and artificial neural network (ANN), the paper presents the relationships between the plastic collapse pressures and tube bend dimensions with various degrees of ovality. It is found that as ovality increases the plastic collapse pressure decreases. Also, the reduction of plastic collapse pressure with ovality is small for a thick tube bend when compared with that for a thin tube bend.

  • (2013) Zhang, Haoyang; Hawkes, Evatt; Chen, Jacqueline; Kook, Sanghoon
    Journal Article
    The autoignition of dimethyl ether (DME) with temperature inhomogeneities is investigated by one-dimensional numerical simulations with detailed chemistry at high pressure and a constant volume. The primary purpose of the study is to provide an understanding of the autoignition of DME in a simplified configuration that is relevant to homogeneous charge compression ignition (HCCI) engines. The ignition structure and the negative temperature coefficient (NTC) behaviour are characterised in a homogeneous domain and one-dimensional domains with thermal stratification, at different initial mean temperatures and length scales. The thermal stratification is shown to strongly affect the spatial structure and temporal progress of ignition. The importance of diffusion and conduction on the ignition progress is assessed. It is shown that the effects of molecular diffusion decay relative to those of chemical reaction as the length-scale increases. This is to be expected, however the present study shows that these characteristics also depend on the mean temperature due to NTC behaviour. For the range of conditions studied here, which encompass a range of stratification length scales expected in HCCI engines, the effects of molecular transport are found to be small compared with chemical reaction effects for mean temperatures within the NTC regime. This is in contrast to previous work with fuels with single-stage ignition behaviour where practically realisable temperature gradients can lead to molecular transport effects becoming important. In addition, thermal stratification is demonstrated to result in significant reductions of the pressure-rise rate (PRR), even for the present fuel with two-stage ignition and NTC behaviour. The reduction of PRR is however strongly dependent on the mean initial temperature. The stratification length-scale is also shown to have an important influence on the pressure oscillations, with large-amplitude oscillations possible for larger length scales typical of integral scales in HCCI engines.

  • (2008) Mak, Lin Chi; Whitty, Mark; Furukawa, Tomonari
    Journal Article
    Purpose – The purpose of this paper is to present a localisation system for an indoor rotary-wing micro aerial vehicle (MAV) that uses three onboard LEDs and base station mounted active vision unit. Design/methodology/approach – A pair of blade mounted cyan LEDs and a tail mounted red LED are used as on-board landmarks. A base station tracks the landmarks and estimates the pose of the MAV in real time by analysing images taken using an active vision unit. In each image, the ellipse formed by the cyan LEDs is used for 5 degree of freedom (DoF) pose estimation with yaw estimation from the red LED providing the 6th DoF. Findings – About 1-3.5 per cent localisation error of the MAV at various ranges, rolls and angular speeds less than 45°/s relative to the base station at known location indicates that the MAV can be accurately localised at 9-12?Hz in an indoor environment. Research limitations/implications – Line-of-sight between the base station and MAV is necessary while limited accuracy is evident in yaw estimation at long distances. Additional yaw sensors and dynamic zoom are among future work. Practical implications – Provided an unmanned ground vehicle (UGV) as the base station equipped with its own localisation sensor, the developed system encourages the use of autonomous indoor rotary-wing MAVs in various robotics applications, such as urban search and rescue. Originality/value – The most significant contribution of this paper is the innovative LED configuration allowing full 6 DoF pose estimation using three LEDs, one camera and no fixed infrastructure. The active vision unit enables a wide range of observable flight as the ellipse generated by the cyan LEDs is recognisable from almost any direction.