1,720,974 research outputs found
Development of a Method for the Fusion of Environment Perception Sensor Data for an Automated Vehicle
No full textAutonomous driving is currently one of the most anticipated future technologies of the automotive world, and researchers from all over the world are dedicated to this task. In the same pursuit, the aDDa project at TU Darmstadt is a collaboration of researchers and students, focused on jointly engineering a car into a fully autonomous vehicle. As such, the aDDa research vehicle is outfitted with a wide array of sensors for environment perception. Within the scope of the aDDa project, this thesis covers the fusion of data from LIDAR, RADAR and camera sensors into a unified environment model. Specifically, this work focuses on providing real-time environment perception, including fusion and interpretation of data from different sensors using only on-board hardware resources. The developed method is a software pipeline, consisting of an analytic low-level sensor fusion stage, a 3D semantic segmentation model based on deep learning, and analytical clustering and tracking methods, as well as a proof-of-concept for estimating drivable space. This method was designed to maximize robustness, by minimizing the influence of the used machine learning approach on the reliability of obstacle detection. The sensor fusion pipeline runs in real-time with an output frequency of 10 Hz, and a pipeline delay of 120 to 190 milliseconds in the encountered situations on public roads. An evaluation of several scenarios shows that the developed system can reliably detect a target vehicle in a variety of real-world situations. The full contributions of this work not only include the development of a sensor fusion pipeline, but also methods for sensor calibration, as well as a novel method for generating training data for the used machine learning approach. In contrast to existing manual methods of data annotation, this work presents a scalable solution for annotating real-world sensor recordings to generate training data for 3D machine perception approaches for autonomous driving
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Analysis of Environmental Influences for Simulation of Active Perception Sensors
Get PDFAutomated vehicles have an inherent safety risk for passengers and other traffic participant. Rigorous testing and safeguarding is needed for approving their operation on public roads. But testing in the real world is not only very time-consuming and expensive but also quite dangerous to participants and the engineers. Therefore more and more tests are relocated to the virtual world before they are performed on proving grounds and eventually in real traffic. In the real world, perception sensors of automated vehicles are subjected to a variety of adverse environmental conditions, such as fog, rain, snow, glaring sun light or road spray from other vehicles. As previous research already showed a severe impact on perception sensors, especially lidar, these influences need to be accurately represented in the virtual world and in models of the perception sensors. To systematically quantify the influence of the named conditions, they are first sorted into two main categories of object independent conditions, such as fog, rain, snow, and object dependent conditions, like wet pavement and road spray. For the first category, measurements in a stationary setup are recorded over a period of six months. Multiple lidar sensors with additional reference sensors for rain rate, temperature, sun brightness, visibility etc. deliver the data in this experiment. The measurements are sorted according to the weather condition and lidar values like the number of detections in the atmosphere are aggregated. This yields expectation values with respect to quantified environmental conditions. As a prominent example for object dependent conditions, road spray is examined in a second experimental setup. Measurements are taken with objects driving over artificially watered pavement on a proving ground. Water film and object velocities are systematically varied between experiment repetitions. The most prominent phenomenon in the recorded data is clustering of detections in the spray plume due to the turbulent nature of the spray. The clustering as well as detection probabilities within these clusters are used as expectation values for modeling. The gathered expectation values are then utilized to develop stochastic simulation models. The models are integrated into an lidar base model in a modular approach compliant to the Open Simulation Interface. The two main modeling approaches are adding false-positive atmospheric detections and attenuating or removing detections generated by the base model. Finally, the gained experiences from the measurements and model development are used to derive requirements for ground truth data quantifying the environmental conditions. The specified ground truth data serves as input to the simulation models
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Entwicklung eines Radar-Sensormodells
Get PDFIn dieser Arbeit wird ein Radar-Sensormodell vorgestellt, das auf einem Fouriertracing-Ansatz basiert. Um die Radarstrahlung im Frequenzbereich zu simulieren, wird ein Raytracing-Verfahren abgewandelt, sodass Radarmessdaten, wie Entfernung, Relativgeschwindigkeit, Azimutwinkel und Leistung, am Ausgang des Raytracers anliegen. Anschließend werden mit diesen Daten die Eigenschaften einer Schnellen Fouriertransformation (FFT) simuliert. Das Radarmodell wird in Vires Virtual Test
Drive (VTD) implementiert. Nach einer Einführung in die Theorie der Radartechnologie und des Raytracings wird ein einfaches Radarmodell mit Fouriertracing vorgestellt. Da das Signal beim Fouriertracing im Frequenzbereich simuliert wird, werden verschiedene Charakteristiken einer FFT, wie die Anwendung von Fensterfunktionen oder durch einen großen Messbereich auftretende Ambiguitäten, berücksichtigt. Außerdem werden Leistungsdämpfungen, z.B. durch das Entfernungsgesetz oder die Antennencharakteristik, implementiert. Durch weitere Anpassung des Raytracers wird die Mehrwegeausbreitung der Radarstrahlen umgesetzt. So werden z.B. Bodenreflexionen berücksichtigt und Ziele, die nicht im direkten Sichtbereich des Radars liegen, von der Strahlung erfasst. In einem weiteren Schritt wird die Rückstrahlleistung bei der Mehrwegeausbreitung genauer betrachtet. Dazu wird zunächst ein Reflektivitätsmodell für Asphalt implementiert. Für die Optimierung spekularer Reflexionen an metallischen Oberflächen wird ein Optimierungsverfahren eingesetzt, das die zu einem Strahl äqui-
valente Fläche nach einem idealen Reflexionspunkt absucht. Jeder Schritt der Modellbildung wird in VTD implementiert und einzeln mit realen Sensordaten verifiziert. Abschließend wird der am Ausgang des Gesamtmodells anliegende Radarwürfel durch Simulation typischer Verkehrsszenarien mit Messdaten der gleichen Szenarien verglichen. So wird das Radarmodell validiert und die Grenzen der Modellbildung aufgeführt
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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