1,386 research outputs found
Prioritizing Strategic IT Projects with Tropos
One of the daily tasks of an enterprise architect is to prioritize strategic IT projects. To achieve a business-IT alignment, this prioritization needs to be based on business strategies and goals. Therefore, business goals and their traceability to strategic IT projects are relevant for the enterprise architect. However, surpris-ingly little formalisations and reasoning techniques have been developed in the enterprise architecture domain. In this paper we show that the popular goal modelling technique Tropos together with its formal reasoning techniques can support the enterprise architect when prioritizing strategic IT projects. We prove the feasibility of our work with a tool implementation of the proposed modelling language and its corresponding algorithms; and demon-strate their usefulness with the help of an example taken from the enterprise architecture literature
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Unsteady Flow and Force Development in the case of a Circular Cylinder
The time varying nature of many real flows has a strong effect on the resulting force experienced by aerodynamic bodies, where the transient force response can readily exceed the steady-state equivalent. This therefore poses a significant threat to small drones as well as larger aircraft that can be subjected to highly unsteady flow fields. Sensing the flow and using predictive modelling to mitigate the unsteady forces shows potential, yet requires a detailed knowledge of the aerodynamic principles at play. This work is a fundamental study into the underlying mechanisms involved in low Reynolds number unsteady aerodynamics to help facilitate future low order models (LOMs). Specifically, the focus is on the development of the unsteady force, by exploring the origin and evolution of boundary layer vorticity as well as the impact of free vorticity located in the flow.
Four sets of experiments are conducted in the towing tank facilities at the University of Cambridge using a rotating and translating circular cylinder as well as a flat plate. To capture the fluid dynamic response, force balance and planar particle image velocimetry (PIV) measurements are acquired in combination, at Reynolds numbers between 4000 and 20000. It is found that whilst the potential flow `added mass' vortex sheet distribution around a stationary object immersed in an accelerating freestream is correct in shape, it ascribes the vortex sheet to the wrong origin. Instead, the vortex sheet is found to develop as a result of external vorticity that is created at the interface between the moving freestream and the quiescent surrounding. Moreover, the evolution of the boundary layer vortex sheet is investigated around a translating and rotating cylinder. The vortex sheet contributions due to kinematics and free vorticity are experimentally recovered. It is further proposed that the vortex sheet contribution due to free vorticity can be decomposed into a local and far-field component. Examining the vortex sheet strength at the unsteady separation point, which has been used in literature explicitly or implicitly to predict unsteady separation, shows that it is strongly affected by the instantaneous velocity, rotation rate and far-field vorticity. Accounting for these contributions collapses the strength of the vortex sheet at the unsteady separation point for the kinematics studied, even as the flow field evolves. In future this may provide avenues with which to predict unsteady separation. Furthermore, the rate at which vorticity sheds from the surface of an object is linked to the boundary layer vortex sheet components. When the unsteady separation point is known, this makes it possible to predict the vorticity shedding rate only from the motion kinematics and the boundary layer vortex sheet.
To minimise computational effort for LOMs, only the most dominant flow physics are ideally modelled. To help determine which flow features therefore need to be incorporated in an LOM, a methodology to approximate the force due to an individual flow structure is proposed. A study of a cylinder encountering a sharp-edged transverse gust explores the force caused by external vorticity located within the gust shear layers. The rigid shear layer assumption inherent in Küssner's model is found to overestimate the related non-circulatory gust force. However, the discrepancy remains small compared to the total force
The weilburg painting showing the lisbon entry of 1619 in its historical and pictorial context
This article deals with the splendid panoramic painting depicting the Joyeuse Entrée of King Philipp III (Filipe II de Portugal) in Lisbon in 1619 which the author discovered at Weilburg castle in Germany. The author places the painting in its historical and pictorial context by comparing it to the written reports of the entry and
comparable 16th and 17th century views of Lisbon. Apparently, the painting is based on a strictly planned choreography that largely follows the previous entry of Philipp II, and is identical in the painted, engraved and written descriptions of the event published between 1619 and 1622.Fundação para a Ciência e a Tecnologia (FCT), Fundação Millennium bc
Randomized Controlled Trial of Imago Relationship Therapy: Exploring Statistical and Clinical Significance
For decades, couples around the world have used Imago relationship therapy (IRT) to improve their relationships. While anecdotal success stories abound, no randomized controlled trial of IRT’s impact has been accomplished until now. The authors review the results of a randomized controlled trial of distressed, treatment-seeking couples who completed 12 sessions of IRT and the impact their involvement had on their marital satisfaction. Results showed that (a) individuals in the treatment condition experienced statistically significant increases in marital satisfaction, while couples in the control group did not; (b) levels of marital satisfaction did decrease significantly from posttreatment to follow-up but remained significantly higher than at pretreatment; (c) though statistically significant, the improvements experienced by the treatment group were not clinically significant improvements; and (d) while approximately one-third of participants achieved recovery during treatment, at the dyad level, only one couple achieved recovery. Further analysis and recommendations for future research are discussed
Mileage-based accident risks of pedelec riders
In a previous paper, we analyzed accidents of pedelec riders in 2019 and examined possible changes over the past years. We found that pedelec accidents still essentially resemble the classic two-wheeler accident characteristics, with certain specifics (e.g., higher age of riders involved in an accident, higher proportion of single-bicycle accidents, higher proportion of out-of-town accidents). Even though the number of pedelecs and pedelec accidents has increased in recent years, no qualitative changes in the characteristics of accidents compared to previous years seem to have occurred.
We now have a large data base of riders and accidents and new data sources that offer the possibility for calculating accident risks by mileage-based analyses. In addition to absolute accident numbers, relative accident parameters are of particular interest for accident research and prevention. Using the same amount of physical effort pedelecs can be used to cover longer distances than bicycles. At the same time, longer distances increase the probability of being involved in an accident. On average, pedelec users cover 1.8 times as many kilometers per day as bicycle users do. We now have nationally representative data on the mileage of pedelec riders, so we can calculate mileage-based accident risks and get new insight into pedelec accidents. For comparison the accident risks of bicycle riders are used
Toward more rigor in ontological analyses
Ontological analyses have been used in numerous publications to compare existing modelling grammars with an ontology. However, a sound theoretical research framework is still missing. Consequently, working with the results of such ontological analyses is theoretically questionable. The aim of the paper is threefold. Firstly, we want to contribute to such a theoretical research framework by formalising the ontological analyses approach. Secondly, we derive four formal requirements each ontological analyses must comply with. Lastly, we analyse whether current state of the art ontological analyses comply with our findings. While the formalisation demonstrates the strengths of the approach we conclude that current ontological analyses have theoretical deficiencies, which lead to serious limitations in their application
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Boundary layer vortex sheet evolution around an accelerating and rotating cylinder
Abstract</jats:p
Cancer Disparities: Unmet Challenges in the Elimination of Disparities
http://dx.doi.org/10.1158/1055-9965.EPI-11-062
Ontology Based Method Engineering
We need conceptual modelling languages to gain domain knowledge in the requirements engineering and analysis phases of an IS development project. These languages should serve an IS expert as means of communication between him or her and the domain expert. Many different modelling languages have been used for conceptual modelling. Consequently, questions relating to the quality of these languages have arisen. Wand, Weber and others have evaluated these languages using an ontology. Each of the languages was found to contain certain deficits. Because our aim is to construct a language without such deficits, we propose the opposite technique. We develop an ontologically clear modelling language for process modelling with the help of the BWW representational model. In addition to this modelling language, we introduce a process model which guides model creation. Both components form a conceptual modelling method
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