Low mass ratio vortex-induced motion

The vortex-induced motion of floating structures is strongly influenced by their low mass ratios (i.e. the ratio of structural to displaced fluid mass). It has previously been demonstrated that the super-upper response branch encountered in two-degree of freedom systems at low mass ratio is characterised by much larger vibration amplitudes than those of the corresponding upper response branch. These low mass ratio super-upper response branch vibrations are clearly of immense importance in the design and analysis of offshore structures. It was the purpose of the current study to experimentally investigate the vortex-induced response of cylindrical structures at low mass ratio with particular emphasis on the relative magnitude of the super-upper response branch vibration amplitudes. The experimental apparatus utilised, consisted of a parallel linkage mechanism allowing translation motion of the cylindrical test section in both the inline and transverse directions. The configuration employed ensured identical mass ratios and natural frequencies in both directions. The mass ratio range covered was nominally 2.4 to 13

Development and Implementation of a Flipped-Classroom Delivery in Engineering Computing and Analysis for First Year Engineering Students

University of Wollongong recently undertook a major restructure of its academic and professional units, after the appointment of a new Vice Chancellor in 2012. As a result, the previous 11 faculties have been merged and rationalised into five new faculties. The Faculty of Engineering and the Faculty of Informatics merged to become the Faculty of Engineering and Information Sciences (EIS), consisting of six schools representing a total of 13 disciplines. Following the restructuring, EIS made the decision to develop a new common first year curriculum for all engineering undergraduate programs, spanning nine disciplines, they being; civil, mining, environmental, electrical, computer, telecommunications, mechanical, materials and mechatronic engineering. The process of developing the new first year subjects was undertaken in 2014 by a Task and Finish (T&F) group aiming for full implementation at the commencement of 2015. Through consultation with key stakeholders from each discipline area, as well as teaching teams from existing first year programs, five new engineering subjects were to be created, to coexist with the unaltered physics and mathematics subjects. The T&F group met regularly over the course of 2014, where they initially tasked with identifying the key mastery skills that all engineering students should have developed by the end of their first year of full time study. These skills were then grouped into themes, leading to the creation of the five new subjects. The final role of the T&F group was to report back to the Heads of School who would then assign key personnel to develop the curriculum content for each new subject. This paper will focus on the development of one of those newly created subjects, ENGG105 Engineering Computing and Analysis, which adopted the flipped-classroom approach to deliver the subject content

Flow-induced vibration mitigation using attached splitter-plates

Prior stationary cylinder studies have continually demonstrated the effectiveness of attached splitter-plates in reducing drag and lift coefficients of cylinders in steady uniform flow. The use of attached splitter-plates has even been reported to be able to completely eliminate vortex shedding in fixed cylinder investigations. In the present study, the proposed utility of attached splitter-plate wake-stabilisation as a passive control mechanism for vortex-induced vibration (VIV) mitigation was investigated. A range of splitter-plate ratios from I/D=O to 4 were examined over a reduced velocity interval of Ur=3 to 60. The addition of splitter-plates resulted in the desired effect of decreasing the maximum drag and lift coefficient values experienced by the bare cylinder. The amplitude response however was markedly increased at low splitter-plate lengths. A galloping type response was observed with the addition of even small splitter-plates to the cylinder. The response of the cylinders at low splitter-plate ratios appeared to be strongly influenced by vortex shedding. Key characteristics of the response such as the abrupt decrease in oscillation amplitude at higher reduced velocity aligned well with the bare cylinder vortex-induced vibration response. With increasing splitter plate ratio, there appears to be a smooth transition from pure vortex-induced vibration to a galloping type response strongly influenced by the vortex shedding at low reduced velocity and a predominantly galloping response at higher reduced velocity. Vibration mitigation was only achieved at splitter-plate lengths of I/D≤2.8 where no significant vortex-induced vibration or galloping type response was observe

The dynamics of a rising pivoted cylinder

The existence of a critical mass ratio for cylinders undergoing vortex-induced vibration (VIV) in a translational system has been well established. Below this critical point, the reduced velocity at VIV lock-out tends to infinity. It has been surmised that a corresponding mass moment of inertia ratio must exist for a pivoted cylinder arrangement. To the authors\u27 knowledge there has been no investigation published substantiating this premise. The aim of the present investigation then was to examine the critical point for cylinders in a rotational system. The approach adopted involved measuring the VIV amplitude response of a positively buoyant, and hence rising, pivoted cylinder at very high reduced velocity. High reduced velocity was attained by establishing a very low system natural frequency through the omission of external restoring forces. The key finding of this study is the presence of a critical point with a value similar to that of the critical mass ratio in translational systems. This critical point does not however appear to be governed by the mass moment of inertia ratio but rather by the force moment ratio

An investigation of international postgraduate engineering students\u27 attitudes and abilities related to avoiding plagiarism

Plagiarism committed by international postgraduate students who come from a non-English speaking background (NESB) has been raised repeatedly as a pressing academic concern. In this study, postgraduate engineering students\u27 views about plagiarism and their ability to detect and avoid plagiarism were examined using a survey instrument. The primary question investigated was whether there was any discernible variation in attitudes and abilities between students from different cultural and linguistic backgrounds. As such, the survey (n=416) was designed to assess students\u27 ability to recognise and rate the severity of plagiarism in a series of writing samples. The responses were collated by birth country and compared by the major geographic regions represented. All participants were invited to give further insight in a post-survey interview where their ability to correct identified plagiarised work was also tested. The results revealed that there were notable differences between the geographical sub-group students\u27 ethical stance and their abilities to identify plagiarism. Furthermore, the variation in attitudes and abilities was still evident after at least a semester of postgraduate study. The plagiarism detection exercise indicated that although the Oceania sub-group were better at identifying plagiarised material, the other sub-groups (consisting entirely of students from either a NESB or with English as a second language) were nearly as proficient. Skill deficiencies and language issues, representing potentially significant disadvantage with respect to academic writing, were evident however when these students were asked to correct the identified plagiarised material

Schema therapy with exposure and response prevention for the treatment of chronic anxiety with comorbid personality disorder

Contains fulltext : 228166.pdf (publisher's version ) (Open Access)Background and objectives: A considerable group of patients with anxiety disorders do not respond to guideline CBT treatment, possibly due to comorbid personality disorder (PD) traits. Schema therapy (ST) is an integrative treatment for personality disorders, and preliminary evidence suggests that it also affects anxiety. The present study examined the effects of a combination treatment ('SCHerp': ST + exposure and response prevention) in a non-responsive outpatient group suffering from chronic anxiety and comorbid cluster C personality disorder. Methods: Psychological malfunction (n = 42), and adaptive and maladaptive schema modes (n = 49) were assessed pre- and post-treatment. Results: Patients showed statistically significant decreases in psychological malfunction and maladaptive modes, and significant increases in adaptive modes from pre- to post-treatment. Changes in modes were correlated with changes in psychological malfunction. Limitations: No control group or follow-up measurements were included. Conclusions: The combination of ST and exposure with response prevention may be a viable avenue for research and treatment for this subpopulation. However, further research is needed to confirm and enhance effectiveness and identify working mechanisms of SCHerp.9 p