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FISITA 2012 World Automotive Congress

作者： Krenek, Thorsten Lauer, Thomas Geringer, Bernhard Christopher, Bacher Institute for Powertrains and Automotive Technology Vienna University of Technology Vienna Austria Institute of Computer Graphics and Algorithms Vienna University of Technology Vienna Austria

ISBN: (纸本)9783642337765

Serial-hybrid-powertrains in extended-range electric vehicles (E-REV) pose different requirements to internal combustion engines (ICE) than conventional vehicles. In E-REVs ICEs are not used for propulsion but for battery charging and cabin heating. This work deals with the design of ICEs in serial-hybrid-powertrains. It considers different operating strategies as well as the dimensioning of the electric components of the powertrain and the thermal management. Therefore, a longitudinal dynamic model was developed using GT-SUITE including the ICE and the thermal management. The engine was operated on a test bench in parallel to create the necessary maps for the numerical investigations. Due to the high amount of parameters that can be optimized when determining the operating strategies and dimensioning the components, by a numerical optimization method that was developed and customized for this problem. The numerical investigations showed that for higher vehicle speeds the direct propulsion of the ICE is more efficient while for lower speeds the operation of the ICE as a generator is the more efficient strategy. Additionally, the influence of the ambient temperature on the efficiency was taken into account. At low ambient temperatures it is necessary to heat up the driver's cabin electrically. Using a thermal numerical model it was possible to show the dependency on the energy consumption, the component dimensioning and the configuration of the operation strategies. The most favourable powertrain setup and the most efficient operating strategies were achieved by using the described numerical optimization method. The new and comprehensive approach was to consider the entire vehicle including mechanical components, thermal components and operating strategies in the numerical model setup and the holistic optimization of them using self-developed numerical optimization software. © 2013 Springer-Verlag.

关键词： Internal combustion engines

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A PILOT/VND/GRASP hybrid for the static balancing of public bicycle sharing systems

A PILOT/VND/GRASP hybrid for the static balancing of public ...

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14th International Conference on computer Aided Systems Theory, EUROCAST 2013

作者： Papazek, Petrina Raidl, Günther R. Rainer-Harbach, Marian Hu, Bin Institute of Computer Graphics and Algorithms Vienna University of Technology Favoritenstrae 9-11/1861 1040 Vienna Austria

ISBN: (纸本)9783642538551

Due to varying user demands in bicycle sharing systems, operators need to actively shift bikes between stations by a fleet of vehicles. We address the problem of finding efficient vehicle tours by an extended version of an iterated greedy construction heuristic following the concept of the PILOT method and GRASP and applying a variable neighborhood descend (VND) as local improvement. Computational results on benchmark instances derived from the real-world scenario in Vienna with up to 700 stations indicate that our PILOT/GRASP hybrid especially scales significantly better to very large instances than a previously proposed variable neighborhood search (VNS) approach. Applying only one iteration, the PILOT construction heuristic followed by the VND provides good solutions very quickly, which can be potentially useful for urgent requests. © 2013 Springer-Verlag Berlin Heidelberg.

关键词： Heuristic methods

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Evaluation of Surround-View and Self-Rotation in the OCTAVIS VR-System 19

Evaluation of Surround-View and Self-Rotation in the OCTAVIS...

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Joint Virtual Reality Conference of 19th Eurographics Symposium on Virtual Environments, EGVE 2013 and 10th Conference and Exhibition of the European Association of Virtual Reality and Augmented Reality, EuroVR 2013

作者： Dyck, Eugen Pfeiffer, Thies Botsch, Mario Computer Graphics Group Bielefeld University Germany Center of Excellence Cognitive Interaction Technology Bielefeld University Germany

ISBN: (纸本)9783905674477

In this paper we evaluate spatial presence and orientation in the OCTAVIS system, a novel virtual reality platform aimed at training and rehabilitation of visual-spatial cognitive abilities. It consists of eight touch-screen displays surrounding the user, thereby providing a 360! horizontal panorama view. A rotating office chair and a joystick in the armrest serve as input devices to easily navigate through the virtual environment. We conducted a two-step experiment to investigate spatial orientation capabilities with our device. First, we examined whether the extension of the horizontal field of view from 135! (three displays) to 360! (eight displays) has an effect on spatial presence and on the accuracy in a pointing task. Second, driving the full eight screens, we explored the effect of embodied self-rotation using the same measures. In particular we compare navigation by rotating the world while the user is sitting stable to a stable world and a self-rotating user. Categories and Subject Descriptors (according to ACM CCS): I.3.6 [computer graphics]: Methodology and Techniques-Interaction techniques. © The Eurographics Association 2013.

关键词： Virtual reality

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Efficient real-time shadows 13

Efficient real-time shadows

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ACM Special Interest Group on computer graphics and Interactive Techniques Conference, SIGGRAPH 2013

作者： Eisemann, Elmar Assarsson, Ulf Schwarz, Michael Valient, Michal Wimmer, Michael Delft University of Technology Netherlands Department of Computer Science and Engineering Chalmers University Sweden Guerrilla Games / Sony Computer Entertainment Netherlands Institute of Computer Graphics and Algorithms Vienna University of Technology Austria

ISBN: (纸本)9781450323390

This course provides an overview of efficient, real-time shadow algorithms. It presents the theoretical background but also discusses implementation details for facilitating efficient realizations (hard and soft shadows, volumetric shadows, reconstruction techniques). These elements are of relevance to both experts and practitioners. The course also reviews budget considerations and analyzes performance trade-offs, using examples from various AAA game titles and film previsualization tools. While physical accuracy can sometimes be replaced by plausible shadows, especially for games, film production requires more pecision, such as scalable solutions that can deal with highly detailed *** course builds upon earlier SIGGRAPH courses as well as the recent book Real-Time Shadows (A K Peters, 2011) by four of the instructors (due to its success, a second edition is planned for 2014). And with two instructors who have worked on AAA game and movie titles, the course presents interesting behindthe-scenes information that illuminates key topics.

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Solving the bi-objective prize-collecting Steiner tree problem with the ε-constraint method

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Electronic Notes in Discrete Mathematics 2013年 41卷 181-188页

作者： Leitner, Markus Ljubić, Ivana Sinnl, Markus Institute of Computer Graphics and Algorithms Vienna University of Technology Vienna Austria Department of Statistics and Operations Research University of Vienna Vienna Austria

In this paper, we study the bi-objective prize-collecting Steiner tree problem, whose goal is to find a subtree that minimizes the edge costs for building that tree, and, at the same time, to maximize the collected node revenues. We propose to solve the problem using an ε-constraint algorithm. This is an iterative mixed-integer-programming framework that identifies one solution for every point on the Pareto front. In this framework, a branch-and-cut approach for the single-objective variant of the problem is enhanced with warm-start procedures that are used to (i) generate feasible solutions, (ii) generate violated cutting planes, and (iii) guide the branching process. Standard benchmark instances from the literature are used to assess the efficacy of our method. © 2013 Elsevier B.V.

关键词： ε-constraint method Bi-objective combinatorial optimization Steiner tree problem

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Balancing bicycle sharing systems: Improving a VNS by efficiently determining optimal loading operations

Balancing bicycle sharing systems: Improving a VNS by effici...

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8th International Workshop on Hybrid Metaheuristics, HM 2013

作者： Raidl, Günther R. Hu, Bin Rainer-Harbach, Marian Papazek, Petrina Institute of Computer Graphics and Algorithms Vienna University of Technology Favoritenstraße 9-11/1861 1040 Vienna Austria

ISBN: (纸本)9783642385155

Public bike sharing systems are important alternatives to motorized individual traffic and are gaining popularity in larger cities worldwide. In order to maintain user satisfaction, operators need to actively rebalance the systems so that there are enough bikes available for rental as well as sufficient free slots for returning them at each station. This is done by a vehicle fleet that moves bikes among the stations. In a previous work we presented a variable neighborhood search metaheuristic for finding effective vehicle routes and three different auxiliary procedures to calculate loading operations for each candidate solution. For the most flexible auxiliary procedure based on LP, the current work provides a new, practically more efficient method for calculating proven optimal loading operations based on two maximum flow computations. The different strategies for determining loading operations are further applied in combination controlled by an additional neighborhood structure. Experimental results indicate that this combined approach yields significantly better results than the original variable neighborhood search. © 2013 Springer-Verlag.

关键词： Optimization

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Implicit mesh generation using volumetric subdivision 13

Implicit mesh generation using volumetric subdivision

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13th Workshop on Virtual Reality Interactions and Physical Simulations, VRIPHYS 2017

作者： Altenhofen, C. Schuwirth, F. Stork, A. Fellner, D. TU Darmstadt Germany Fraunhofer IGD Germany Graz University of Technology Institute of Computer Graphics and Knowledge Visualization Austria

ISBN: (纸本)9783038680321

In this paper, we present a novel approach for a tighter integration of 3D modeling and physically-based simulation. Instead of modeling 3D objects as surface models, we use a volumetric subdivision representation. Volumetric modeling operations allow designing 3D objects in similar ways as with surface-based modeling tools. Encoding the volumetric information already in the design mesh drastically simplifies and speeds up the mesh generation process for simulation. The transition between design, simulation and back to design is consistent and computationally cheap. Since the subdivision and mesh generation can be expressed as a precomputable matrix-vector multiplication, iteration times can be greatly reduced compared to common modeling and simulation setups. Therefore, this approach is especially well suited for early-stage modeling or optimization use cases, where many geometric changes are made in a short time and their physical effect on the model has to be evaluated frequently. To test our approach, we created, simulated and adapted several 3D models. Additionally, we measured and evaluated the timings for generating and applying the matrices for different subdivision levels. For comparison, we also measured the tetrahedral meshing functionality offered by CGAL for similar numbers of elements. For changing topology, our implicit meshing approach proves to be up to 70 times faster than creating the tetrahedral mesh only based on the outer surface. Without changing the topology and by precomputing the matrices, we achieve a speed-up of up to 2800. © 2017 The Author(s) Eurographics Proceedings 2017 The Eurographics Association.

关键词： Mesh generation

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Using a serious game approach to teach 'operator precedence' to introductory programming students

Using a serious game approach to teach 'operator precedence'...

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2013 17th International Conference on Information Visualisation, IV 2013

作者： Adamo-Villani, Nicoletta Haley-Hermiz, Thomas Cutler, Robb Department of Computer Graphics Technology Purdue University West Lafayette IN United States Department of Computer Science Purdue University West Lafayette IN United States

ISBN: (纸本)9780769550497

In this paper we describe the design, development, formative evaluation and initial findings of one level of a serious game whose objective is to teach Information Assurance concepts to undergraduate students in introductory programming courses. The game level focuses on the concept of 'operator precedence'. The player travels through a multilevel 3- dimensional maze and at each junction in the maze he/she is required to solve a mathematical problem that involves the application of operator precedence rules. A correct answer allows the player to move closer to the maze exit, an incorrect solution moves the player farther from the end of the maze. Initial findings from a formative study with a group of 14 undergraduate students show that the game level is usable, engaging and useful for learning/reviewing the intended programming concept. © 2013 IEEE.

关键词： Serious games

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Enhancing a genetic algorithm with a solution archive to reconstruct cross cut shredded text documents

Enhancing a genetic algorithm with a solution archive to rec...

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14th International Conference on computer Aided Systems Theory, EUROCAST 2013

作者： Biesinger, Benjamin Schauer, Christian Hu, Bin Raidl, Günther R. Institute of Computer Graphics and Algorithms Vienna University of Technology Favoritenstraße 9-11/1861 1040 Vienna Austria

ISBN: (纸本)9783642538551

In this work the concept of a trie-based complete solution archive in combination with a genetic algorithm is applied to the Reconstruction of Cross-Cut Shredded Text Documents (RCCSTD) problem. This archive is able to detect and subsequently convert duplicates into new yet unvisited solutions. Cross-cut shredded documents are documents that are cut into rectangular pieces of equal size and shape. The reconstruction of documents can be of high interest in forensic science. Two types of tries are compared as underlying data structure, an indexed trie and a linked trie. Experiments indicate that the latter needs considerably less memory without affecting the run-time. While the archive-enhanced genetic algorithm yields better results for runs with a fixed number of iterations, advantages diminish due to the additional overhead when considering run-time. © 2013 Springer-Verlag Berlin Heidelberg.

关键词： Genetic algorithms

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Diverse trajectory planning for UAV control displays

Diverse trajectory planning for UAV control displays

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12th International Conference on Autonomous Agents and Multiagent Systems 2013, AAMAS 2013

作者： Tožička, Jan Balata, Jan Míkovec, Zdeněk Agent Technology Center Dept. of Computer Science Prague Czech Republic Department of Computer Graphics and Interaction FEE Czech Technical University Prague Czech Republic

ISBN: (纸本)9781627487665

Current UAV control systems can plan optimal trajectories with respect to predefined constraints (waypoints, no-fly zones). However when the operator is not satisfied with planned trajectories it is usually very complicated to force the system to change the trajectories in desired way. In this demonstration we solve this problem by innovative UAV control display based on diverse planning algorithm. Copyright © 2013, International Foundation for Autonomous Agents and Multiagent Systems (***). All rights reserved.

关键词： Unmanned aerial vehicles (UAV)

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