Rigid body mode identification of the PAH-2 helicopter using the eigensystem realization algorithm

The rigid body modes of the PAH-2 'Tiger' helicopter were identified using the Eigensystem Realization Algorithm (ERA). This work complements ground vibration tests performed using DLR's traditional phase resonance technique and the ISSPA (Identification of Structural System Parameters) method. Rigid body modal parameters are important for ground resonance prediction. Time-domain data for ERA were obtained by inverse Fourier transformation of frequency response functions measured with stepped-sine excitation. Mode purity (based on the Phase Resonance Criterion) was generally equal to or greater than corresponding results obtained in the ground vibration tests. All identified natural frequencies and mode shapes correlate well with corresponding ground vibration test results. The modal identification approach discussed in this report has become increasingly attractive in recent years due to the steadily declining cost and increased performance of scientific computers. As illustrated in this application, modern time-domain methods can be successfully applied to data acquired using DLR's existing test equipment. Some suggestions are made for future applications of time domain modal identification in this manner

Renewable energy and its impact on agricultural and rural development: Findings of a comparative study in Central, Eastern and Southern Europe

Rising energy prices for fossil fuels, the unreliable supply of energy imports during the last winters and - concerning the 12 new members states (NMS) - the demand by the European Union (EU) for developing National Renewable Energy Action Plans have stimulated the national discussion and political action on renewable energy (RE) among all European countries. Particularly among the 12 NMS the share of RE has increased during the last years. Among the candidate and potential candidate countries (CC and PCC) the discussion on RE has just started. When looking at the impact of RE on agricultural and rural development the effects are relatively small. An expansion of rape seed cultivation and, to a smaller extent, of the production of wood pellets could be observed. But overall the impact of RE on agricultural and rural income and employment seems to be marginal up to now. Whether it will be so in the future, depends on national policies and support programme as none of the various types of RE is competitive to fossil fuels for the time being. -- Die öffentliche Diskussion sowie die politischen Maßnahmen im Hinblick auf erneuerbare Energien haben im Laufe der vergangenen Jahre bei allen europäischen Staaten erheblich zugenommen. Die Gründe liegen bei den stetig steigenden Preisen für fossile Energieträger, den unzuverlässigen Lieferungen in den vergangenen Wintern sowie - besonders bei den 12 Neuen Mitgliedsstaaten (NMS) der Europäischen Union (EU) - die verbindliche Maßgabe, einen Nationalen Aktionsplan für Erneuerbare Energien zu entwickeln. Besonders innerhalb der 12 NMS hat der Anteil der erneuerbaren Energie am Gesamtenergieverbrauch zugenommen. Allerdings sind die Auswirkungen der erweiterten Nutzung von erneuerbaren Energien auf die landwirtschaftliche und ländliche Entwicklung bis dato relativ gering. Lediglich eine Ausweitung des Rapsanbau sowie in einem geringerem Maße von Holzpellets war zu beobachten. Die Auswirkungen auf Einkommen und Beschäftigung sind jedoch (noch) marginal. Inwieweit sich dies in der Zukunft ändern wird, hängt von den nationalen Politiken und Unterstützungsprogrammen ab, da bis jetzt keine Art der erneuerbaren Energien gegenüber den fossilen Brennstoffen konkurrenzfähig ist.Renewable energy,comparative survey,agricultural and rural development,New members states of the EU,candidate and potential candidate countries,Erneuerbare Energien,vergleichende Analyse,landwirtschaftliche und ländliche Entwicklung,Neue Mitgliedsstaaten sowie (potenzielle) Beitrittsländer der EU.

Eigensystem realization algorithm modal identification experiences with mini-mast

This paper summarizes work performed under a collaborative research effort between the National Aeronautics and Space Administration (NASA) and the German Aerospace Research Establishment (DLR, Deutsche Forschungsanstalt fur Luft- und Raumfahrt). The objective is to develop and demonstrate system identification technology for future large space structures. Recent experiences using the Eigensystem Realization Algorithm (ERA), for modal identification of Mini-Mast, are reported. Mini-Mast is a 20 m long deployable space truss used for structural dynamics and active vibration-control research at the Langley Research Center. A comprehensive analysis of 306 frequency response functions (3 excitation forces and 102 displacement responses) was performed. Emphasis is placed on two topics of current research: (1) gaining an improved understanding of ERA performance characteristics (theory vs. practice); and (2) developing reliable techniques to improve identification results for complex experimental data. Because of nonlinearities and numerous local modes, modal identification of Mini-Mast proved to be surprisingly difficult. Methods were available, ERA, for obtaining detailed, high-confidence results

Human Posterior Parietal Cortex Plans Where to Reach and What to Avoid

In this time-resolved functional magnetic resonance imaging (fMRI) study, we aimed to trace the neuronal correlates of covert planning processes that precede visually guided motor behavior. Specifically, we asked whether human posterior parietal cortex has prospective planning activity that can be distinguished from activity related to retrospective visual memory and attention. Although various electrophysiological studies in monkeys have demonstrated such motor planning at the level of parietal neurons, comparatively little support is provided by recent human imaging experiments. Rather, a majority of experiments highlights a role of human posterior parietal cortex in visual working memory and attention. We thus sought to establish a clear separation of visual memory and attention from processes related to the planning of goal-directed motor behaviors. To this end, we compared delayed-response tasks with identical mnemonic and attentional demands but varying degrees of motor planning. Subjects memorized multiple target locations, and in a random subset of trials targets additionally instructed (1) desired goals or (2) undesired goals for upcoming finger reaches. Compared with the memory/attention-only conditions, both latter situations led to a specific increase of preparatory fMRI activity in posterior parietal and dorsal premotor cortex. Thus, posterior parietal cortex has prospective plans for upcoming behaviors while considering both types of targets relevant for action: those to be acquired and those to be avoided

Space representation for eye movements is more contralateral in monkeys than in humans

Contralateral hemispheric representation of sensory inputs (the right visual hemifield in the left hemisphere and vice versa) is a fundamental feature of primate sensorimotor organization, in particular the visuomotor system. However, many higher-order cognitive functions in humans show an asymmetric hemispheric lateralization—e.g., right brain specialization for spatial processing—necessitating a convergence of information from both hemifields. Electrophysiological studies in monkeys and functional imaging in humans have investigated space and action representations at different stages of visuospatial processing, but the transition from contralateral to unified global spatial encoding and the relationship between these encoding schemes and functional lateralization are not fully understood. Moreover, the integration of data across monkeys and humans and elucidation of interspecies homologies is hindered, because divergent findings may reflect actual species differences or arise from discrepancies in techniques and measured signals (electrophysiology vs. imaging). Here, we directly compared spatial cue and memory representations for action planning in monkeys and humans using event-related functional MRI during a working-memory oculomotor task. In monkeys, cue and memory-delay period activity in the frontal, parietal, and temporal regions was strongly contralateral. In putative human functional homologs, the contralaterality was significantly weaker, and the asymmetry between the hemispheres was stronger. These results suggest an inverse relationship between contralaterality and lateralization and elucidate similarities and differences in human and macaque cortical circuits subserving spatial awareness and oculomotor goal-directed actions

Fusion-kitsch des arts performatifs chez Marcel Proust1

Marcel Proust’s novels certify kitsch by the presence of architecture, theater and fashion. The writer produced his works using textual accumulation and hybridization. These two processes call for other arts in romantic production. From this point of view, the baroque, gothic and modern architectures are represented in the texts through buildings tested by rhetorical descriptions. Images of theater and opera scenes accentuate the flow of kitsch. Ostentatious mode creations are also notified in the intrigues. Marcel Proust is inspired by performing arts to develop an aesthetic of plurality in his novels.Marcel Proust’s novels certify kitsch by the presence of architecture, theater and fashion. The writer produced his works using textual accumulation and hybridization. These two processes call for other arts in romantic production. From this point of view, the baroque, gothic and modern architectures are represented in the texts through buildings tested by rhetorical descriptions. Images of theater and opera scenes accentuate the flow of kitsch. Ostentatious mode creations are also notified in the intrigues. Marcel Proust is inspired by performing arts to develop an aesthetic of plurality in his novels

Quantitatively consistent computation of coherent and incoherent radiation in particle-in-cell codes - a general form factor formalism for macro-particles

Quantitative predictions from synthetic radiation diagnostics often have to consider all accelerated particles. For particle-in-cell (PIC) codes, this not only means including all macro-particles but also taking into account the discrete electron distribution associated with them. This paper presents a general form factor formalism that allows to determine the radiation from this discrete electron distribution in order to compute the coherent and incoherent radiation self-consistently. Furthermore, we discuss a memory-efficient implementation that allows PIC simulations with billions of macro-particles. The impact on the radiation spectra is demonstrated on a large scale LWFA simulation.Comment: Proceedings of the EAAC 2017, This manuscript version is made available under the CC-BY-NC-ND 4.0 licens