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We present a system that combines voxel and polygonal representations into a single octree acceleration structure that can be used for ray tracing. Voxels are well-suited to create good level-of-detail for high-frequency models where polygonal simplifications usually fail due to the complex structure of the model. However, polygonal descriptions provide the higher visual fidelity. In addition, voxel representations often oversample the geometric domain especially for large triangles, whereas a few polygons can be tested for intersection more quickly.
The proper use of protective hoods on panel saws should reliably prevent severe injuries from (hand) contact with the blade or material kickbacks. It also should minimize long-term lung damages from fine-particle pollution. To achieve both purposes the hood must be adjusted properly by the operator for each workpiece to fit its height. After a work process is finished, the hood must be lowered down completely to the bench. Unfortunately, in practice the protective hood is fixed at a high position for most of the work time and herein loses its safety features. A system for an automatic height adjustment of the hood would increase comfort and safety. If the system can distinguish between workpieces and skin reliably, it furthermore will reduce occupational hazards for panel saw users. A functional demonstrator of such a system has been designed and implemented to show the feasibility of this approach. A specific optical sensor system is used to observe a point on the extended cut axis in front of the blade. The sensor determines the surface material reliably and measures the distance to the workpiece surface simultaneously. If the distance changes because of a workpiece fed to the machine, the control unit will set the motor-adjusted hood to the correct height. If the sensor detects skin, the hood will not be moved. In addition a camera observes the area under the hood. If there are no workpieces or offcuts left under the hood, it will be lowered back to the default position.
The steadily decreasing prices of display technologies and computer graphics hardware contribute to the increasing popularity of multiple-display environments, like large, high-resolution displays. It is therefore necessary that educational organizations give the new generation of computer scientists an opportunity to become familiar with this kind of technology. However, there is a lack of tools that allow for getting started easily. Existing frameworks and libraries that provide support for multi-display rendering are often complex in understanding, configuration and extension. This is critical especially in educational context where the time that students have for their projects is limited and quite short. These tools are also rather known and used in research communities only, thus providing less benefit for future non-scientists. In this work we present an extension for the Unity game engine. The extension allows – with a small overhead – for implementation of applications that are apt to run on both single-display and multi-display systems. It takes care of the most common issues in the context of distributed and multi-display rendering like frame, camera and animation synchronization, thus reducing and simplifying the first steps into the topic. In conjunction with Unity, which significantly simplifies the creation of different kinds of virtual environments, the extension affords students to build mock-up virtual reality applications for large, high-resolution displays, and to implement and evaluate new interaction techniques and metaphors and visualization concepts. Unity itself, in our experience, is very popular among computer graphics students and therefore familiar to most of them. It is also often employed in projects of both research institutions and commercial organizations; so learning it will provide students with qualification in high demand.
An Empirical Evaluation of the Received Signal Strength Indicator for fixed outdoor 802.11 links
(2015)
For the evaluation of the received signal strength indication (RSSI) a different methodology compared to previous publications is introduced in this paper by exploiting a spectral scan feature of recent Qualcomm Atheros WiFi NICs. This method is compared to driver reports and to an industrial grade spectrum analyzer. During the conducted outdoor experiments a decreased scattering of the RSSI compared to previous publications is observed. By applying well-known mathematical tests for normality it is possible to show that the RSSI does not follow a normal distribution in a line-of-sight outdoor environment. The evaluated spectral scan features offers additional possibilities to develop interference classifiers which is an important step for frequency allocation in long-distance 802.11 networks.
With a focus on Technology Enhanced Learning, this paper investigates if and to which extent a culture shift can be expected alongside with the adoption of currently emerging Web 3.0 technologies. Instead of just offering new opportunities for the field to improve education, such a culture shift could lead to unexpected general consequences not just for Technology Enhanced Learning but the whole educational sector. Understanding the dimension of expectable changes enables us to prevent conflicts and pointedly support culture-related change processes. After an introduction of the Revised Onion Model of Culture, which, later on, serves as theoretical foundation, expectable changes in the design of learning scenarios are analysed, distinguishing the stakeholder groups “learners” and “educators”. Eventually, the found changes are analysed to which extent a general culture shift is to be expected in order to understand the transferability and limitations of future research results in the field.
Annual Report 2013 - 2014
(2015)
This paper proposes an Artificial Plasmodium Algorithm (APA) mimicked a contraction wave of a plasmodium of physarum polucephalum. Plasmodia can live using the contracion wave in their body to communicate to others and transport a nutriments. In the APA, each plasmodium has two information as the wave information: the direction and food index. We apply APA to a maze solving and route planning of road map.
This book chapter describes application examples of gas chromatography/mass spectrometry and pyrolysis – gas chromatography/mass spectrometry in failure analysis for the identification of chemical materials like mineral oils and nitrile rubber gaskets. Furthermore, failure cases demanding identification of polymers/copolymers in fouling on the compressor wall of a car air conditioner and identification of fouling on the surface of a bearing race from the automotive industry are demonstrated. The obtained analytical results were then used for troubleshooting and remedial action of the technological process.
Appropriating Digital Fabrication Technologies — A comparative study of two 3D Printing Communities
(2015)
Digital fabrication technologies have a great potential for empowering consumers to produce their own creations. However, despite the growing availability of digital fabrication technologies in shared machine shops such as FabLabs or University Labs, they are often perceived as difficult to use, especially by users with limited technological aptitude. Hence, it is not yet clear if the potentials of the technology can be made accessible to a broader public, or if they will remain limited to some form of “maker elite”. In this paper, we study the appropriation of digital fabrication on the example of the use of 3D printers in two different communities. In doing so, we analyze how users conceptualize their use of the 3D printers, what kind of contextual understanding is necessary to work with the machines, and how users document and share their knowledge. Based on our empirical findings, we identify the potentials that the machines offer to the communities, and what kind of challenges have to be overcome in their appropriation of the technology.
This paper proposes a new artificial neural network-based maximum power point tracker for photovoltaic application. This tracker significantly improves efficiency of the photovoltaic system with series-connection of photovoltaic modules in non-uniform irradiance on photovoltaic array surfaces. The artificial neural network uses irradiance and temperature sensors to generate the maximum power point reference voltage and employ a classical perturb and observe searching algorithm. The structure of the artificial neural network was obtained by numerical modelling using Matlab/Simulink. The artificial neural network was trained using Bayesian regularisation back-propagation algorithms and demonstrated a good prediction of the maximum power point. Relative number of Vmpp prediction errors in range of ±0.2V is 0.05% based on validation data.
This book presents bond graph model-based fault detection with a focus on hybrid system models. The book addresses model design, simulation, control and model-based fault diagnosis of multidisciplinary engineering systems. The text beings with a brief survey of the state-of-the-art, then focuses on hybrid systems. The author then uses different bond graph approaches throughout the text and provides case studies.
We propose a high-performance GPU implementation of Ray Histogram Fusion (RHF), a denoising method for stochastic global illumination rendering. Based on the CPU implementation of the original algorithm, we present a naive GPU implementation and the necessary optimization steps. Eventually, we show that our optimizations increase the performance of RHF by two orders of magnitude when compared to the original CPU implementation and one order of magnitude compared to the naive GPU implementation. We show how the quality for identical rendering times relates to unfiltered path tracing and how much time is needed to achieve identical quality when compared to an unfiltered path traced result. Finally, we summarize our work and describe possible future applications and research based on this.
Only since the turn of the 21st century have humanitarian organisations developed specific strategies that address climate change impacts as a humanitarian challenge. Taking the International Red Cross / Red Crescent Movement, being the largest humanitarian network, as an empirical case study, the article discusses the Movement’s changes in the areas 1) agenda setting, 2) organisational restructuring, 3) networking, 4) programming, and 5) advocacy. Based on the case study and a theoretical framework of organisational sociology, the article provides conclusions on internal and external factors that can explain why the Movement has been successful in being one of the first actors within the organisational field of humanitarian organisations to focus systematically on the humanitarian implications of climatic changes.
Communicating Climate Risks. A case study of the International Red Cross/Red Crescent Movement
(2015)
Comparison of the subject-oriented and the Petri net based approach for business process automation
(2015)
The subject-oriented modelling approach [5] significally differs from the classic Petri net based approach of many business process modeling languages like EPC [9], Business Process Model and Notation (BPMN) [11], and also Yet Another Workflow Language (YAWL) [10]. In this work, we compare the two approaches by modeling a case study called "Procure to Pay"[3], a typical business process where some equipment for a construction site is rented and finally paid. The case study is not only modelled but also automated using the Metasonic Suite for the subject-oriented and YAWL for the Petri net based approach.
Competitions for Benchmarking: Task and Functionality Scoring Complete Performance Assessment
(2015)
Over the last 50 years, the controlled motion of robots has become a very mature domain of expertise. It can deal with all sorts of topologies and types of joints and actuators, with kinematic as well as dynamic models of devices, and with one or several tools or sensors attached to the mechanical structure. Nevertheless, the domain has not succeeded in standardizing the modelling of robot devices (including such fundamental entities as “reference frames”!), let alone the semantics of their motion specification and control. This thesis aims to solve this long-standing problem, from three different sides: semantic models for robot kinematics and dynamics, semantic models of all possible motion specification and control problems, and software that can support the latter while being configured by a systematic use of the former.
Communicating Sequential Processes (CSP) [7] is a calculus for concurrent systems that has been the basis of subject-oriented business process management (S-BPM) [4]. We use CSPm -- a machine readable dialect of CSP -- to create a sequence of models for a case study on an "Automated Teller Machine" [1]. We use the refinement checker FDR2 to prove that certain models are correct implementations of specifications.
The aim of our research is finding measures to preserve the learners’ initial motivation in educational settings. For that we need to avoid conflicting situations that possibly could jeopardize their joy of learning.
In our thematically comprehensive Learning Culture Survey, we investigate the cultural biasing of students’ attitudes, behaviours, and expectations towards education. Particularly in times of massive international migration and growing numbers of refugees, the relevance to deeply understand cultural aspects in education increases. Just with this understanding, we can raise the awareness towards more cultural tolerance across all involved stakeholder groups and thus, foster the development of more culture-sensitive educational approaches. In this paper we focus on the most relevant aspect of motivation and comparatively discuss our study conducted in Germany and South Korea.
Mit unserer Forschung wollen wir Maßnahmen finden, die dazu beitragen, die anfängliche
Bildungsmaßnahmen zu
Motivation von Lernern bewahren. Zu diesem Zweck
in müssen Konfliktsituationen möglichst vermieden werden, wenn sie das Potential haben, ihnen die Freude am Lernen zu verderben. In unserem thematisch breitgefächerten Learning Culture Survey (Untersuchung von Lernkultur), untersuchen wir bei Lernern das Vorhandensein und den Einfluss kulturspezifischer Prägungen auf deren Verhaltensweisen, Gewohnheiten und Erwartungen bzgl. Bildung. Besonders in Zeiten massiver internationaler Migration und steigender Zahlen von Flüchtlingen wächst der Bedarf nach entsprechender Forschung stetig an. Nur wenn wir die Zusammenhänge zwischen Lernen und Kultur ausreichend verstehen, sind wir in der Lage, auf allen Ebenen die Entwicklung des erforderlichen Bewusstseins bzgl. kultursensibler Bildungsansätze zu fördern. In diesem Beitrag konzentrieren wir uns auf den sehr wichtigen Aspekt Motivation und diskutieren die Ergebnisse, die wir in unserer vergleichenden Studie in Deutschland und Südkorea erzielt haben.