202 research outputs found

    Unsteady, Transonic Flow Around Delta Wings Undergoing Coupled and Natural Modes Response: A Multidisciplinary Problem

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    The unsteady, three-dimensional Navier-Stokes equations coupled with the Euler equations of rigid-body dynamics are sequentially solved to simulate and analyze the aerodynamic response of a high angle of attack delta wing undergoing oscillatory motion. The governing equations of fluid flow and dynamics of the multidisciplinary problem are solved using a time-accurate solution of the laminar, unsteady, compressible, full Navier- Stokes equations with the implicit, upwind, Roe flux-difference splitting, finite-volume scheme and a four-stage Runge-Kutta scheme, respectively. The primary model under consideration consists of a 65 deg swept, sharp-edged, cropped delta wing of zero thickness at 20 deg angle of attack. In a freestream of Mach 0.85 and Reynolds number of 3.23 x 10(exp 6), the flow over the upper surface of the wing develops a complex shock system which interacts with the leading-edge primary vortices producing vortex breakdown. The effect of the oscillatory motion of the wing on the vortex breakdown and overall aerodynamic response is detailed to provide insight to the complicated physics associated with unsteady flows and the phenomenon of wing rock. Forced sinusoidal single and coupled mode rolling and pitching motion is presented for the wing in a transonic freestream. The Reynolds number, frequency of oscillation, and the phase angle are varied. Comparison between the single and coupled mode forced rolling and pitching oscillation cases illustrate the effects of coupling the motion. This investigation shows that even when coupled, forced rolling oscillation at a reduced frequency of 2(pi) eliminates the vortex breakdown which results in an increase in lift. The coupling effect for in phase forced oscillations show that the lift coefficient of the pitching-alone case and the rolling-moment coefficient of the rolling-alone case dominate the resulting response. However, with a phase lead in the pitching motion, the coupled motion results in a non-periodic response of the rolling moment. The second class of problems involve releasing the wing in roll to respond to the flowfield. Two models of sharp-edged delta wings, the previous 65 deg swept model and an 80 deg swept, sharp-edged delta wing, are used to observe the aerodynamic response of a wing free to roll in a transonic and subsonic freestream, respectively. These cases demonstrate damped oscillations, self-sustained limit cycle oscillations, and divergent rolling oscillations. Ultimately, an active control model using a mass injection system was applied on the surface of the wing to suppress the self-sustained limit cycle oscillation known as wing rock. Comparisons with experimental investigations complete this study, validating the analysis and illustrating the complex details afforded by computational investigations

    Caretaker conventions in Australasia: minding the shop for government

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    In this monograph, Anne Tiernan and Jennifer Menzies capably chart the often hazardous terrain of the \u27caretaker period\u27 that ensues from the time an election is called until a new government is formed. This is a landscape fraught with political and administrative dangers - particularly for public servants who are required to \u27mind the shop\u27 and keep the basic machinery of government going. The conventions represent an historical accretion of custom, practice and rules, often leavened with uncertainty. In tackling their subject, Tiernan and Menzies draw upon their shared past experiences as public servants and ministerial \u27staffer\u27 as well as the highest standards of academic scholarship - this is a \u27must read\u27 for politicians, public servants and students of government

    Caretaker conventions in Australasia: minding the shop for government

    Get PDF
    In this monograph, Anne Tiernan and Jennifer Menzies capably chart the often hazardous terrain of the ‘caretaker period’ that ensues from the time an election is called until a new government is formed. This is a landscape fraught with political and administrative dangers – particularly for public servants who are required to ‘mind the shop’ and keep the basic machinery of government going. The conventions represent an historical accretion of custom, practice and rules, often leavened with uncertainty. In tackling their subject, Tiernan and Menzies draw upon their shared past experiences as public servants and ministerial ‘staffers’ as well as the highest standards of academic scholarship – this is a ‘must read’ for politicians, public servants and students of government

    Weight optimum arch structures

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    This investigation is concerned with the optimization of arch structures. The DOT optimization code is used to minimize the volume of such arch structures which are constrained by limits on stress, design geometry, and section dimensions. Modeling the arch structure by a series of bar-beam elements, the finite elements method is used to compute element stresses. The DOT optimization code selects section dimensions to prevent failure due to element stresses exceeding the material yield stress. Specifically, through coordinate transformations between local element coordinates and global systems coordinates the element stiffness matrices transform into the global stiffness matrix. The resulting system matrix equations are then solved for the system degrees of freedom, that is, displacements and slopes. The system degrees of freedom, in turn, are then transformed back to the element level to computer the internal forces and moments and hence, the stresses. Results are presented for a number of cases with regard to optimization scheme and stress analysis.http://archive.org/details/weightoptimumarc00menzLieutenant, United States NavyApproved for public release; distribution is unlimited

    Cost-Effectiveness of Skin Surveillance Through a Specialized Clinic for Patients at High Risk of Melanoma

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    Purpose Clinical guidelines recommend that people at high risk of melanoma receive regular surveillance to improve survival through early detection. A specialized High Risk Clinic in Sydney, Australia was found to be effective for this purpose; however, wider implementation of this clinical service requires evidence of cost-effectiveness and data addressing potential overtreatment of suspicious skin lesions. Patients and Methods A decision-analytic model was built to compare the costs and benefits of specialized surveillance compared with standard care over a 10-year period, from a health system perspective. A high-risk standard care cohort was obtained using linked population data, comprising the Sax Institute’s 45 and Up cohort study, linked to Medicare Benefits Schedule claims data, the cancer registry, and hospital admissions data. Benefits were measured in quality-adjusted life-years gained. Sensitivity analyses were undertaken for all model parameters. Results Specialized surveillance through the High Risk Clinic was both less expensive and more effective than standard care. The mean saving was A6,828(956,828 (95% CI, 5,564 to $8,092) per patient, and the mean quality-adjusted life-year gain was 0.31 (95% CI, 0.27 to 0.35). The main drivers of the differences were detection of melanoma at an earlier stage resulting in less extensive treatment and a lower annual mean excision rate for suspicious lesions in specialized surveillance (0.81; 95% CI, 0.72 to 0.91) compared with standard care (2.55; 95% CI, 2.34 to 2.76). The results were robust when tested in sensitivity analyses. Conclusion Specialized surveillance was a cost-effective strategy for the management of individuals at high risk of melanoma. There were also fewer invasive procedures in specialized surveillance compared with standard care in the community

    Recruiting for Epigenetic Research: Facilitating the Informed Consent Process

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    Because the effects of epigenetic (gene-environment interaction) changes have been associated with numerous adverse health states, the study of epigenetic measures provides exciting research opportunities for biobehavioral scientists. However, recruitment for studies focusing on any aspect of genetics poses challenges. Multiple factors, including lack of knowledge regarding a research study, have been identified as barriers to recruitment. Strengthening the informed consent process through extended discussion has been found to be effective in recruiting for research studies in general, yet there is a paucity of information that focused on such a recruitment strategy for epigenetic studies. In this paper, we share our experiences with strategies to strengthen the informed consent process as well as provide samples of materials developed to heighten potential participants’ understanding of epigenetics, in 4 epigenetic research studies with women from diverse backgrounds experiencing a range of health issues. The combined enrollment success rate for epigenetic studies using the process was 89% with participants representing a diverse population. We posit that carefully developed recruitment scripts provided a foundation for improving potential participants’ understanding of the research project. Easy to understand illustrations of the epigenetic process provided a basis for active engagement and encouraged individual questions

    Psychoeducational intervention for people at high risk of developing another melanoma: a pilot randomised controlled trial

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    Introduction Information and psychological needs have been reported as one of the greatest areas of unmet needs for patients with melanoma. To respond to these needs, we developed the Melanoma Care Intervention, a developed psychoeducational intervention for people at high risk of developing another melanoma comprising of a newly developed melanoma educational booklet and individually tailored telephone support sessions provided by trained psychologists. The purpose of this study was to investigate the acceptability and feasibility of the Melanoma Care Intervention. Methods Twenty-four adults (14 men, 10 women, mean age: 58 years, SD: 12.2) at high risk of developing a subsequent primary melanoma were recruited and randomly assigned 1:1 to the intervention (a psychoeducational booklet, a Cancer Council booklet on melanoma and up to five telephone-based sessions with a psychologist) or usual care (Cancer Council booklet only). Acceptability, feasibility, fear of cancer recurrence and secondary psychosocial outcomes were assessed at baseline, 1 and 6 months. Results Satisfaction and perceived benefits were rated highly for all intervention components, particularly the telephone-based psychology sessions (mean satisfaction and benefits: both 9.27 out of 10, SD=2.41). The quality of information and support provided throughout the trial was rated as ‘high’ by the intervention group, with a mean score of 4.6 out of a possible 5 (SD=0.9) and 4.2 (SD=1.2) for the control group. Conclusions The intervention was feasible and acceptable for improving psychological adjustment. Timely access to effective, evidence-based, psychological care is a recognised need for people with melanoma. The intervention is designed to directly address this need in a way that is feasible in a clinical setting, acceptable to patients and health professionals

    A randomised controlled feasibility study of group cognitive behavioural therapy for people with severe asthma

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    Objectives: Evidence for the efficacy of Cognitive Behavioural Therapy (CBT) in asthma is developing but it is not known if this translates to benefits in severe asthma or if a group approach is acceptable to this patient group. This study aimed to assess the feasibility and acceptability of Group-CBT in severe asthma. Method: This was a two-centre, randomised controlled parallel group feasibility study. Eligible participants (patients with severe asthma and a clinically significant diagnosis of anxiety and/or depression – Hospital Anxiety and Depression Scale (HAD) score greater than 8 for the anxiety or depression sub-scale) received Group-CBT in weekly sessions for eight consecutive weeks and usual care or usual care only. Follow-up was for 16 weeks and end points were: Asthma Quality of Life Questionnaire, Asthma Control Questionnaire, HAD, Dyspnoea-12, EuroQual-5D and EuroQuol-VAS. Results: 51 patients were randomised: 36% (51 out of 140) consent rate and 25% (13/51) attrition at week 16. Screening logs indicated that study take-up was influenced by patients living long distances from the treatment centre and inability to commit to the weekly demands of the programme. Drop-out was higher in Group-CBT compared due to inability to commit to the weekly programme because of poor health. Participants who contributed to focus group discussions reported that Group-CBT contributed to a better understanding of their illness and related approaches to anxiety management and acceptance of their asthma condition. Although weekly face-to-face sessions were challenging, this was the preferred method of delivery for these participants. Conclusions: This feasibility study shows that Group-CBT warrants further investigation as a potentially promising treatment option for patients with severe asthma. It has been possible but not easy to recruit and retain the sample. Options for a less demanding intervention schedule, such as less frequent face-to-face visits and the use of web-based interventions, require careful consideration

    A randomised controlled feasibility trial of Group Cognitive Behavioural Therapy for people with severe asthma

    Get PDF
    Evidence for the efficacy of Cognitive Behavioural Therapy (CBT) in asthma is developing but it is not known if this translates to benefits in severe asthma or if a group approach is acceptable to this patient group. This study aimed to assess the feasibility and acceptability of Group-CBT in severe asthma.This was a two-centre, randomised controlled parallel group feasibility study. Eligible participants (patients with severe asthma and a clinically significant diagnosis of anxiety and/or depression - Hospital Anxiety and Depression Scale (HAD) score greater than 8 for the anxiety or depression sub-scale) received Group-CBT in weekly sessions for eight consecutive weeks and usual care or usual care only. Follow-up was for 16 weeks and end points were: Asthma Quality of Life Questionnaire, Asthma Control Questionnaire, HAD, Dyspnoea-12, EuroQual-5D and EuroQuol-VAS.51 patients were randomised: 36% (51 out of 140) consent rate and attrition at week 16 was 12. Screening logs indicated that study take-up was influenced by patients living long distances from the treatment centre and inability to commit to the weekly demands of the programme. Drop-out was higher in Group-CBT compared due to inability to commit to the weekly programme because of poor health. Participants who contributed to focus group discussions reported that Group-CBT contributed to a better understanding of their illness and related approaches to anxiety management and acceptance of their asthma condition. Although weekly face-to-face sessions were challenging, this was the preferred method of delivery for these participants.This feasibility study shows that Group-CBT warrants further investigation as a potentially promising treatment option for patients with severe asthma. It has been possible but not easy to recruit and retain the sample. Options for a less demanding intervention schedule, such as less frequent face-to-face visits and the use of web-based interventions, require careful consideration
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