674 research outputs found
F.W. Angel memorial lecture ; 1970; F.W. Angel memorial lecture, 1970
No full textThe Third Annual F.W. Angel Memorial Lectur
Author Correction:A 41,500 year-old decorated ivory pendant from Stajnia Cave (Poland)
No full textCorrection to: Scientific Reports https://doi.org/10.1038/s41598-021-01221-6, published online 25 November 2021The original version of this Article contained errors in the author list where Marjolein D. Bosch was omitted from the author list, and Mikołaj Urbanowski was incorrectly listed as an author of the original Article, and has subsequently been removed.The Author contributions section now reads:“S.T. W.N. and A.N. conceived the project; S.T., W.N., A.P., M.B., S.C., M.D., H.F., A.M., M.D. B., D.P., M.P.R., C.M.R., V.S-M., G.M.S., P.S., M.S., K.S., A.V., F.W., H.W., A.W., M.Z., S.B., A.N., J-J. H., performed research; S.T., A.P., W.N., M.B., M.D.B., S.C., M.D., H.F., A.M., D.P., M.P.R., C.M.R., V.S-M., G.M.S., P.S., M.S., K.S., A.V., F.W., H.W., A.W., M.Z., S.B., A.N., J-J. H. analysed all archaeological data; S.T. and A.P. wrote the paper with the collaboration of all the co-authors.”The original Article and its accompanying Supplementary Information file have been corrected
Transforming Power Relationships: Leadership, Risk, and Hope. IHS Political Science Series No. 135, May 2013
No full textChronic communal conflicts resemble the prisoner’s dilemma. Both communities prefer peace to war. But neither trusts the other, viewing the other’s gain as its own loss, so
potentially shared interests often go unrealized.
Achieving positive-sum outcomes from apparently zero-sum struggles requires a kind of riskembracing leadership. To succeed leaders must: a) see power relations as potentially
positive-sum; b) strengthen negotiating adversaries instead of weakening them; and c) demonstrate hope for a positive future and take great personal risks to achieve it.
Such leadership is exemplified by Nelson Mandela and F.W. de Klerk in the South African democratic transition. To illuminate the strategic dilemmas Mandela and de Klerk faced, we examine the work of Robert Axelrod, Thomas Schelling, and Josep Colomer, who highlight important dimensions of the problem but underplay the role of risk-embracing leadership. Finally we discuss leadership successes and failures in the Northern Ireland settlement and the Israeli-Palestinian conflict
Interactive visualisation techniques for large time-dependent data sets
No full textThe research described in this thesis was part of a larger research project about multi-phase flows. These flows are characterised by a sharp transition between the fluids, the so-called phase front. One of the goals of the project was to study the evolution of the phase fronts using CFD, i.e. to study the development of the surfaces over time and to understand how they change and interact with each other. In order to study the evolving fronts, methods were needed for detecting and extracting them in the first place, and subsequently for tracking the phase fronts over time, and finding a way to visualise them interactively. The focus of this research was directed towards efficient techniques for interactive isosurfacing from very large time-dependent data sets. Fast-access data structures that were designed to perform one particular visualisation task efficiently were examined first. These data structures make use of the properties of a particular visualisation algorithm and are made to fit the algorithm closely. The advantage of data structures like these is that they are designed to perform a particular visualisation task very fast. However, the drawback is that they are also limited to perform only that visualisation task. The second approach that was explored is the use of multi-resolution data structures. These structures enable the data to be accessed at several levels of resolution. A multi-resolution data structure provides the flexibility to switch between different visualisations and is designed to handle large data sets by trading off data resolution for speed. This multi-resolution approach was extended to time-dependent data sets. Techniques for region-of-interest selection and time-window management were added to provide interactive visualisation and space-time navigation of these large 4D data sets.Electrical Engineering, Mathematics and Computer Scienc
Multiple-view feature modelling with model adjustment
No full textMultiple-view feature modeling is a product development approach that combines concurrent engineering and feature modeling. It supports applications from various phases of product development, by providing an own interpretation of, or view on, a product for each of these applications. The approach can lead to higher quality of products in less time, which is one of the most important goals of contemporary product development. This thesis shows that a multiple-view feature modeling approach can also support the earlier phases of the product development process, by describing views that support conceptual and assembly design, and their integration with views that support part detail design and manufacturing planning. In addition, it shows that automatic model adjustment is a feasible and useful technique in feature modeling.Electrical Engineering, Mathematics and Computer Scienc
Scientific visualization in virtual reality: Interaction techniques and application development
No full textThe research described in this thesis was carried out in the Computer Graphics & CAD/CAM group at Delft University of Technology. The project was directly supervised by Frits Post. It is the sixth project in a series of PhD projects on data visualization, but the first project concerned with Virtual Reality and data visualization. In summer 1998, the Responsive Workbench facility was installed at the High Performance Applied Computing Center (HPaC) at TU Delft. The Workbench was intended to serve as a high performance visualization system, working in a cluster with the other HPaC supercomputers. This PhD project was initiated to set up an environment for high-performance data visualization, so that our group and other research groups of TU Delft could use this VR facility. Another aspect was to include computational steering facilities, which would enable the user to control a supercomputer simulation directly from the virtual environment displayed on the Workbench. For the purposes of our research we developed the RWB Library and the VRX toolkit, together a basic environment for visualization and interaction on the RWB. The thesis covers three main topics: design and development of VR applications, interaction in virtual environments, and visualization of data, originating from scientific simulations. On various case studies we have demonstrated that the Responsive Workbench concept with our software and techniques can provide an efficient visualization environment with natural spatial interaction. The case studies were done in co-operation with internal TU Delft and external research groups. One of the early applications was an interactive 3D visualization of the flooding risk simulations, provided by WL|Delft Hydraulics. The Molecular Dynamics visualization and computational steering case study has been conducted in close co-operation with the Computational Physics group (Faculty of Applied Sciences, TU Delft). The visualization of atmospheric data, originating from cumulus clouds simulations, has been performed together with the Thermal and Fluids Sciences group (Faculty of Applied Sciences, TU Delft).Electrical Engineering, Mathematics and Computer Scienc
Ray Tracing for Real-time Games
No full textThis thesis describes efficient rendering algorithms based on ray tracing, and the application of these algorithms to real-time games. Compared to rasterizationbased approaches, rendering based on ray tracing allows elegant and correct simulation of important global effects, such as shadows, reflections and refractions. The price for these benefits is performance: ray tracing is compute-intensive. This is true if we limit ourselves to direct lighting and specular light transport, but even more so if we desire to include diffuse and glossy light transport. Achieving high performance by making optimal use of system resources and validating results in real-life scenarios are central themes in this thesis. We validate, combine and extend existing work into several complete and well-optimized renderers. We apply these to a number of games. We show that ray tracing leads to more realistic graphics, efficient game production, and elegant rendering software. We show that physically-based rendering will be feasible in real-time games within a few years.Computer Graphics & VisualizationElectrical Engineering, Mathematics and Computer Scienc
Constraint-based feature validation
No full textThe feature modeling paradigm combines geometric and functional product information in one model. In an ideal product development environment, multiple views of a product in terms of features coexist. Feature validation concerns the validity of the feature information in all these views, focusing on validity specification and maintenance. This thesis presents a feature validation scheme based on constraints. It enables flexible and expressive feature validity maintenance. The scheme ensures that only meaningful products can be specified, and that their validity is maintained under product modifications from different views.Electrical Engineering, Mathematics and Computer Scienc
Human-computer interaction and presence in virtual reality exposure therapy
No full textElectrical Engineering, Mathematics and Computer Scienc
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