Filtern
Erscheinungsjahr
- 2017 (42) (entfernen)
Dokumenttyp
Sprache
- Englisch (42) (entfernen)
Volltext vorhanden
- nein (42) (entfernen)
Schlagworte
This paper presents a novel approach to build consistent 3D maps for multi robot cooperation in USAR environments. The sensor streams from unmanned aerial vehicles (UAVs) and ground robots (UGV) are fused in one consistent map. The UAV camera data are used to generate 3D point clouds that are fused with the 3D point clouds generated by a rolling 2D laser scanner at the UGV. The registration method is based on the matching of corresponding planar segments that are extracted from the point clouds. Based on the registration, an approach for a globally optimized localization is presented. Apart from the structural information of the point clouds, it is important to mention that no further information is required for the localization. Two examples show the performance of the overall registration.
Global registration of heterogeneous ground and aerial mapping data is a challenging task. This is especially difficult in disaster response scenarios when we have no prior information on the environment and cannot assume the regular order of man-made environments or meaningful semantic cues. In this work we extensively evaluate different approaches to globally register UGV generated 3D point-cloud data from LiDAR sensors with UAV generated point-cloud maps from vision sensors. The approaches are realizations of different selections for: a) local features: key-points or segments; b) descriptors: FPFH, SHOT, or ESF; and c) transformation estimations: RANSAC or FGR. Additionally, we compare the results against standard approaches like applying ICP after a good prior transformation has been given. The evaluation criteria include the distance which a UGV needs to travel to successfully localize, the registration error, and the computational cost. In this context, we report our findings on effectively performing the task on two new Search and Rescue datasets. Our results have the potential to help the community take informed decisions when registering point-cloud maps from ground robots to those from aerial robots.
In this experimental work we present a novel electrolyzer system for the production of hydrogen and oxygen at high pressure levels without an additional mechanical compressor. Due to its control strategies, the operation conditions for this electrolyzer can be kept optimal for each load situation of the system. Furthermore, the novel system design allows for dynamic long-term operation as well as for easy maintainability. Therefore, the device meets the requirements for prospective power-to-gas applications, especially, in order to store excess energy from renewable sources. A laboratory scale device has been developed and high-pressure operation was validated. We also studied the long-term stability of the system by applying dynamic load cycles with load changes every 30 sec. After 80 h of operation the used membrane electrode assembly (MEA) was investigated by means of SEM, EDX and XRD analysis.
CoCoSpot: Clustering and recognizing botnet command and control channels using traffic analysis
(2017)
This study investigates differences between treatment plans generated by Ray Tracing (RT) and Monte Carlo (MC) calculation algorithms in homogeneous and heterogeneous body regions. Particularly, we focus on the head and on the thorax, respectively, for robotic stereotactic radiotherapy and radiosurgery with Cyberknife. Radiation plans for tumors located in the head and in the thorax region have been calculated and compared to each other in 47 cases and several tumor types.
Corporate Social Responsibility and Diversity Management. Theoretical Approaches and Best Practices
(2017)
Environmental rocking ratchet: Environmental rectification by a harmonically driven avoided crossing
(2017)
We propose a rocking ratchet designed as a symmetric quantum two-state system driven by a single periodic harmonic force and influenced symmetrically by thermal fluctuations. We show that the necessary broken symmetry can dynamically be achieved by a thermal environment that couples to the energy difference between the two states and the tunnel coupling between them. The quantum two-state system is driven by the harmonic periodic drive through its avoided crossing. The correspondingly driven dissipative quantum dynamics results on average in a finite population difference between both states. This then causes directed particle transport.
There is a strongly held belief that if companies can direct their marketing activities to improve customer attitudes and intentions, it will impact on purchase behaviors. Departing from complementary yet sometimes conflicting findings of the current literature, we intend to contribute to the literature by answering two related questions. First, we investigate drivers of loyalty intention over time, and by so doing try to better understand loyalty formation. Second, once we understand loyalty formation, we assess the impact of loyalty on different aspects of purchase behavior, considering temporal effects. Therefore, we develop a consumption-system model which assumes that perceptions, intention, and the impact of perceptions and intention on behavior in one period serve as anchors for the same constructs in a subsequent period, implying a pattern of repeated consumption over time.
Using 3SLS regression analysis, results of a large-scale study using survey data from a sample of 2,478 customers from two points in time and purchase data gathered over a 30-month period suggest interesting findings on the two aforementioned questions:
Considering the first question, we find strong support for customer equity drivers directly influencing loyalty. Moreover, we see evidence for loyalty formation as a consumption-system as equity drivers and loyalty intention of one period are significant predictors of the same constructs in the next period.
Addressing the second research question is less straightforward. We find a significant impact of loyalty intention only for purchase frequency, but not for future sales and average receipt. This suggests that in a retailing context, the amount spent depends to a larger extent on actual needs and not on loyalty intention. Loyalty intention seems to be a more appropriate lead indicator for the frequency of store visits. For most categories, repurchase intention will not necessarily be related to higher sales. On the contrary, higher future sales are more likely to depend on the retailer’s ability to cross- and up-sell to its customers. In all, we need to acknowledge that the strongest predictor of future behavior is, in fact, past behavior.
These results question some of the strongly held beliefs of relationship marketing and its impact on actual behavior. Effects might not be as simple as they appear at first, i.e., temporal interplay between constructs. Moreover, it seems that inertia is more important than some marketing research tends to acknowledge. We would therefore suggest a more detailed investigation of customers’ initial choice behavior. If, in fact, inertia is the driving force behind purchase behavior, companies need to augment their emphasis on increasing initial customer contact and, accordingly, on initial product trial. This is somewhat counter-intuitive from a relationship marketing perspective, because that stream of research largely suggests the advantage of retaining customers rather than acquiring new ones. While we are not denying the importance of customer retention, it seems that companies are already fairly successful in doing so – the strong inertia effect confirms that. Hence, customer retention might not be the best strategy to differentiate in the market. Perhaps companies can better differentiate by excelling in customer acquisition. This, however, would have a significant impact on how marketing budgets should be spent by companies trying to reach sustained success. It might be time for re-balancing customer acquisition and customer retention.
The technology of polymer electrolyte membrane (PEM) electrolysis provides an efficient way to produce hydrogen. In combination with renewable energy sources, it promises to be one of the key factors towards a carbon-free energy infrastructure in the future. Today, PEM electrolyzers with a power consumption higher than 1 MW and a gas output pressure of 30 bar (or even higher) are already commercially available. Nevertheless, fundamental research and development for an improved efficiency is far from being finally accomplished, and mostly takes place on a laboratory scale. Upscaling the laboratory prototypes to an industrial size usually cannot be achieved without facing further problems and/or losing efficiency. With our novel system design based on hydraulic cell compression, a lot of the commonly occurring problems like inhomogeneous temperature and current distribution can be avoided. In this study we present first results of an upscaling by a factor of 30 in active cell area.