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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.
In der vorliegenden Arbeit wird ein neuartiges Verfahren zur Echtzeitüberwachung von Laserbohrprozessen vorgestellt. Die Untersuchungen werden an unterschiedlichen Materialien unter Einsatz eines passiv-gütegeschalteten Nd:YAG Lasers durchgeführt. Prozessbegleitend findet eine Aufzeichnung der akustischen Emissionen mit anschließender Analyse durch schnelle Fourier-Transformation statt. Hierdurch lassen sich der Durchbruch beim Bohren durch ein Material sowie der Materialübergang mehrschichtiger Systeme detektieren. Die akustischen Messungen werden durchAuswertung der Pulsfolge des Lasers mittels einer Fotodiode gestützt. Hierbei zeigt sich eine gute Übereinstimmung der im akustischen Spektrum dominanten Frequenz mit der jeweils im Laserburstauftretenden Pulsfrequenz. Das vorgestellte Verfahren ermöglicht eine Echtzeitüberwachung beim Laserbohren mittels kostengünstiger und einfacher Hardware. Zudem zeichnet es sich im Gegensatz zu bestehenden Verfahren durch eine hohe Robustheit gegen äußere Störeinflüsse aus, da eine frequenzbasierte Auswertung stattfindet.
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.
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.
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.
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.
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.
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.
Die Vielzahl der Möglichkeiten, um mit Kunden in den Dialog zu treten, ist erheblich gestiegen. Unternehmen sind deshalb gefordert, die verschiedenen Kontaktkanäle mit ihren Kunden systematisch zu managen. Im Mittelpunkt steht dabei der Informations- und Entscheidungsprozess des Kunden, der als Customer Journey bezeichnet wird. Diese Journey ist definiert als Prozess zwischen dem ersten Kaufimpuls und der Kaufentscheidung. Dieser Prozess ist charakterisiert von der Nutzung verschiedener Medien bzw. Kontaktkanäle. Kunden nutzen die Kontaktkanäle, die ihnen in der aktuellen Situation als sehr einfach bzw. bequem erscheinen und zu ihren spezifischen Anliegen (Fragen zum Produkt, Bestellung etc.) passen. Erfahrungen zeigen, dass sich zwar Grundmuster identifizieren lassen, ansonsten die Wege der Kunden jedoch sehr individuell sein können.
Internes Qualitätsmanagement (QM) wurde spätestens 2007 mit dem Gesetz zur Stärkung des Wettbewerbs in der gesetzlichen Krankenversicherung zu einem wesentlichen Bestandteil der stationären medizinischen Rehabilitation (Petri, Stähler, 2008). Seit dem Auslaufen der Übergangsfrist am 01.10.2012 verfügen alle durch einen gesetzlichen Rehabilitationsträger belegten stationären Einrichtungen über ein, den Anforderungen der Bundesarbeitsgemeinschaft für Rehabilitation entsprechendes, zertifiziertes QM-System.
Für das IT-Service-Management, also für die Maßnahmen zur Planung, Überwachung und Steuerung der Effektivitat und Effizienz von IT-Services, existieren Standardprozessmodelle wie beispielsweise ITIL oder MOF. Kleine und mittlere Unternehmen (KMU) können für das IT-Service-Management oftmals nicht die IT-Service-Management-Prozesse aus ITIL oder MOF nutzen, da der zusätzliche administrative Aufwand zur Nutzung für diese Unternehmen meist nicht rentabel ist. Dies ist ein entscheidender Wettbewerbsnachteil, da die Aufgaben und Themen im IT-Service-Management für KMU der in großen Unternehmen sehr ähnlich sind.
Die Autoren ermitteln in diesem Beitrag typische Anforderungen an das IT-Service-Management in KMU, entwickeln anschliesend ein für KMU geeignetes Prozessmodell für das IT-Service-Management, das sich aus ITIL ableitet, und beschreiben abschließend die exemplarische Einführung in einem Unternehmen.
Solar energy is one option to serve the rising global energy demand with low environmental Impact [1]. Building an energy system with a considerable share of solar power requires long-term investment and a careful investigation of potential sites. Therefore, understanding the impacts from varying regionally and locally determined meteorological conditions on solar energy production will influence energy yield projections. Clouds are moving on a short term timescale and have a high influence on the available solar radiation, as they absorb, reflect and scatter parts of the incoming light [2]. However, modeling photovoltaic (PV) power yields with a spectral resolution and local cloud information gives new insights on the atmospheric impact on solar energy.
Reducing energy consumption is one of the most pursued economic and ecologic challenges concerning societies as a whole, individuals and organizations alike. While politics start taking measures for energy turnaround and smart home energy monitors are becoming popular, few studies have touched on sustainability in office environments so far, though they account for almost every second workplace in modern economics. In this paper, we present findings of two parallel studies in an organizational context using behavioral change oriented strategies to raise energy awareness. Next to demonstrating potentials, it shows that energy feedback needs must fit to the local organizational context to succeed and should consider typical work patterns to foster accountability of consumption.
In the fermentation process sugars are transformed into lactic acid. pH meters have traditionally been used for fermentation process monitoring based on acidity. More recently, near infrared (NIR) spectroscopy has proven to provide an accurate and non-invasive method to detect when the transformation of sugars into lactic acid is finished. The fermentation process when sugars are transformed into lactic acid. This research proposes the use of simplified NIR spectroscopy using multispectral optical sensors as a simpler and less expensive measure to end the fermentation process. The NIR spectrum of milk and yogurt is compared to find and extract features that can be used to design a simple sensor to monitor the yogurt fermentation process. Multispectral images in four selected wavebands within the NIR spectrum are captured and show different spectral remission characteristics for milk, yogurt and water, which support the selection of these wavebands for milk and yogurt classification.
A novel approach to produce 2D designs by adapting the HyperNEAT algorithm to evolve non-uniform rational basis splines (NURBS) is presented. This representation is proposed as an alternative to previous pixel-based approaches primarily motivated by aesthetic interests, and not designed for optimization tasks. This spline representation outperforms previous pixel-based approaches on target matching tasks, performing well even in matching irregular target shapes. In addition to improved evolvability in the face of a well defined fitness metric, a NURBS representation has the added virtues of being continuous rather than discrete, as well as being intuitive and easily modified by graphic and industrial designers.
We present GEM-NI -- a graph-based generative-design tool that supports parallel exploration of alternative designs. Producing alternatives is a key feature of creative work, yet it is not strongly supported in most extant tools. GEM-NI enables various forms of exploration with alternatives such as parallel editing, recalling history, branching, merging, comparing, and Cartesian products of and for alternatives. Further, GEM-NI provides a modal graphical user interface and a design gallery, which both allow designers to control and manage their design exploration. We conducted an exploratory user study followed by in-depth one-on-one interviews with moderately and highly skills participants and obtained positive feedback for the system features, showing that GEM-NI supports creative design work well.