1,100 research outputs found

    FUN3D and USM3D Analysis of the Propulsion Aerodynamic Workshop 2018 S-Duct Test Case

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    This work presents the results of Fun3D and USM3D analyses that were performed for the 4th AIAA Propulsion Aerodynamics Workshop (PAW). The PAW workshop is separated into three sections that focus on internal duct flows, nozzle flows and a special topic. This paper focuses on the internal duct flow section of PAW04 while an accompanying paper discusses the analyses performed for the nozzle portion. For the internal duct flow section, the PAW04 participants were provided with the two configurations consisting of an S-duct with and without aerodynamic interface plane (AIP) rake legs modeled. The participants were asked to perform a grid refinement study as well as a turbulence model study for the configuration with the rake legs. The analyses discussed here were performed on custom grids developed under the guidelines of the workshop. Additionally, the paper discusses the development and use of flow controllers for matching the desired flow characteristics. The results show that both solvers do well for predicting internal flow characteristics of the S-duct based on direct comparison with the experimental data. However, the CFD-to-CFD comparison proved to be more challenging due to the localized occurrence of supersonic flow near the rake legs when using the mass flow controller. A turbulence model study was performed to compare the two-equation SST model to the SA-QCR model. The results show that although the turbulence model does affect the solution, it makes a minimal impact on pressure recovery and inlet distortion intensity for this case. Suggestions for future workshops include gridding guidelines similar to those employed for the Drag Prediction Workshop series for the grid refinement study and a time accuracy study

    Intra-Abdominal Hypertension and Abdominal Compartment Syndrome in Association with Ruptured Abdominal Aortic Aneurysm in the Endovascular Era: Vigilance Remains Critical

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    Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are common complications of ruptured abdominal aortoiliac aneurysms (rAAAs) and other abdominal vascular catastrophes even in the age of endovascular therapy. Morbidity and mortality due to systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF) are significant. Recognition and management of IAH are key critical care measures which may decrease morbidity and improve survival in these vascular patients. Two strategies have been utilized: expectant management with prompt decompressive laparotomy upon diagnosis of threshold levels of IAH versus prophylactic, delayed abdominal closure based upon clinical parameters at the time of initial repair. Competent management of the abdominal wound with preservation of abdominal domain is also an important component of the care of these patients. In this review, we describe published experience with IAH and ACS complicating abdominal vascular catastrophes, experience with ACS complicating endovascular repair of rAAAs, and techniques for management of the abdominal wound. Vigilance and appropriate management of IAH and ACS remains critically important in decreasing morbidity and optimizing survival following catastrophic intra-abdominal vascular events

    External control and red tape: the mediating effects of client and organizational feedback

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    Bozeman’s (1993, 2000) external control model of red tape posits that organizations with higher degrees of external control will have higher levels of red tape. According to the model, this is compounded by entropy affecting the communication of rules and their results, limited discretion over rules and procedures, and non-ownership of rules. However, the model predicts that red tape will be mediated by communication from clients and within the organization. Bozeman’s model is often cited in the literature, but it has not been subjected to empirical verification. This study tests the model using data from a multiple informant survey of 136 upper tier English local governments conducted in 2004 and several secondary sources. Statistical results show that external control does indeed lead to higher levels of red tape. We then test a number of organizational feedback mediators and find that client feedback does little to mediate the effects of red tape; the major factor is trust between politicians and officers. We discuss these findings and propose some changes to the model.postprin

    FUN3D and USM3D Analysis of the 4th AIAA Propulsion Aerodynamics Workshop Nozzle Test Case

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    This work presents the results of FUN3D and USM3D analyses that were performed for the 4th AIAA Propulsion Aerodynamics Workshop. The workshop was separated into three sections that focus on internal duct flows, nozzle flows, and a special topic of interest. This paper focuses on the nozzle section while an accompanying paper discusses the analyses performed for the internal duct flow section. For the nozzle flow section, the participants were provided with two configurations consisting of a rectangular convergent nozzle with and without an aft-deck. User-generated grids were developed under the guidelines of the workshop for the present analyses. The results show that both solvers compare favorably to the experimental results for the baseline nozzle with the largest differences observed at the lower NPR values. Additionally, both solvers showed favorable agreement with the experimental data for the pressures on the surface of the aft-deck. However, neither solver was able to match the jet flow further downstream for the nozzle with aft-deck configuration. A turbulence model study was conducted to compare the two-equation SST model, SA-QCR model, and two-equation k-kL model (FUN3D only). The results show that the SA-QCR turbulence model was unable to match the experimental results downstream of the nozzle. The k-kL model was shown to better match the experimental data compared to the SST model for most cases simulated using the FUN3D flow solver. Suggestions for future workshops include gridding guidelines similar ion Workshop series for the grid refinement study and a reduction in scope to allow for more detailed exploration of the individual problems. rticipation by reducing time requirement

    The governance of formal university–industry interactions: understanding the rationales for alternative models

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    This article develops a conceptual framework to explain the economic rationale underpinning the choice of different modes of governance of formal university–industry interactions: personal contractual interactions, where the contract regulating the collaboration involves a firm and an individual academic researcher, and institutional interactions, where the relationship between the firm and the academic is mediated by the university. Although institutional interactions, for numerous reasons, have become more important, both governance modes are currently being implemented. We would argue that they have some important specificities that need to be understood if university–industry knowledge transfer is to be managed effectively and efficiently

    Goats or wolves? Private sector managers in the public sector

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    Public administration reforms have propagated the use of private sector management skills in the public sector, and an increased openness to managers with a private sector background. This has created a debate between those who think private sector experience improves public institutions by bringing core managerial values such as results orientation, efficiency, or openness to innovation, and those who argue that private sector experience can damage core public sector values, such as impartiality and equity. Despite the abundant anecdotal evidence, broad empirical evidence on the effects of private sector experience on public managers' values remains limited. Using data from a survey among central government top managers in 18 European countries, we show that public managers with private sector experience have, as expected, more core managerial values. Yet, unlike the conventional view, core public values do not suffer.The politics and administration of institutional chang

    Engaging national organizations for knowledge translation: Comparative case studies in knowledge value mapping

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    <p>Abstract</p> <p>Background</p> <p>Government sponsors of research and development, along with their funded investigators, are increasingly tasked with demonstrating evidence of knowledge use by nontraditional audiences. This requires efforts to translate their findings for effective communication. For technology-related knowledge, these audiences include clinicians, consumers, manufacturers, public policy agencies, and knowledge brokers. One potentially efficient approach is to communicate research findings through relevant national organizations. However, this requires an understanding of how such organizations view and treat research knowledge, which can be determined through knowledge-value mapping. Do knowledge values differ between national organizations representing different audiences? Can a deeper understanding of knowledge values help sponsors, investigators, and organizations better communicate research findings to stakeholders?</p> <p>Methods</p> <p>A series of comparative case studies on knowledge-value mapping were derived through interviews with spokespersons for six national organizations. The semi-structured interviews followed a 10-item questionnaire to characterize different ways in which each organization engages with research-based knowledge. Each participating organization represents a particular stakeholder group, while all share a common interest in the research subject matter.</p> <p>Results</p> <p>Each national organization considers the value of the research knowledge in the context of their organization's mission and the interests of their members. All are interested in collaborating with researchers to share relevant findings, while they vary along the following dimensions of knowledge engagement: create, identify, translate, adapt, communicate, use, promote, absorptive capacity, and recommendations for facilitation.</p> <p>Conclusions</p> <p>The principles of knowledge translation suggest that investigators can increase use by tailoring the format and context of their findings to the absorptive capacity of nonscholars. Greater absorption should result in higher levels of knowledge awareness, interest, and use, which can then be documented. National organizations and their members, in turn, can strive to optimize their absorptive capacities regarding the state of the sciences. This combination will ensure the highest possible return on public investment in research activities. This knowledge-value mapping study concludes that national organizations are appropriate channels for communicating research findings and for meeting statutory requirements and general expectations for generating and documenting knowledge use.</p
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