5,049 research outputs found
Luminescence petrography of the Apollo 12 rocks and comparative features in terrestrial rocks and meteorites Final report
Luminescence petrography of Apollo 12 rocks and comparative features in Apollo 11 rocks, terrestrial rocks, and meteorite
What about local climate governance? A review of promise and problems
A large proportion of greenhouse gas emissions is produced in urban areas, particularly in high income countries. Cities are also vulnerable to the impacts of climate change, and particularly so in developing countries. Therefore, local climate policies for mitigation and adaptation have to play an important role in any effective global climate protection strategy. Based upon a systematic literature review, this article gives a comprehensive overview of motivation and challenges for local climate governance. A large part of the literature focuses on mitigation and cities in industrialized countries. The review also includes the smaller and emerging body of literature on adaptation and cities in developing or industrializing countries. Motivations and challenges we find fall into broad categories like ‘economic’, ‘informational’, ‘institutional’, ‘liveability’ or ‘political/cultural’. We conclude that the mix of motivation and challenges is city-specific, and that the national framework conditions are important. It matters, whether cities engage in mitigation or adaptation policies, whether they are located in developing, industrializing or industrialized countries, and at which stage of climate policy-making cities are. For many cities, cost savings are a primary motivation for local mitigation policies, while perceived vulnerability and a commitment to development is the primary motivator for adaptation policies. The collective action problem of climate protection (also known as ‘Tragedy of the Commons’) and inappropriate legal frameworks are key barriers to mitigation policies. Challenges for adaptation include financial constraints, and a lack of expertise, cooperation, leadership and political support. Understanding their specific motivation and challenges may support cities in developing appropriate local climate action plans. Furthermore, the understanding of motivation and challenges can inform other policy levels that want to help realize the local climate protection potential.Climate policy, local authorities, cities, mitigation, adaptation, energy, local climate governance
Nonlinear dynamics of river runoff elucidated by horizontal visibility graphs
Horizontal Visibility Graphs (HVGs) are a recently developed method to construct networks from time series. The values of the time series are considered as the nodes of the network and are linked to each other if there is no larger value between them, such as they can “see” each other. The network properties reflect the nonlinear dynamics of the time series. For some classes of stochastic processes and for periodic time series, analytical results can be obtained for network-derived quantities such as the degree distribution, the local clustering coefficient distribution, the mean path length, and others. HVGs have the potential to discern between deterministic-chaotic and correlated-stochastic time series. Here, we investigate the sensitivity of the HVG methodology to properties and pre-processing of real-world data, i.e., time series length, the presence of ties, and deseasonalization, using a set of around 150 runoff time series from managed rivers at daily resolution from Brazil with an average length of 65 years. We show that an application of HVGs on real-world time series requires a careful consideration of data pre-processing steps and analysis methodology before robust results and interpretations can be obtained. For example, one recent analysis of the degree distribution of runoff records reported pronounced sub-exponential “long-tailed” behavior of North American rivers, whereas another study of South American rivers showed hyper-exponential “short-tailed” behavior resembling correlated noise. We demonstrate, using the dataset of Brazilian rivers, that these apparently contradictory results can be reconciled by minor differences in data-preprocessing (here: small differences in subtracting the seasonal cycle). Hence, data-preprocessing that is conventional in hydrology (“deseasonalization”) changes long-term correlations and the overall runoff dynamics substantially, and we present empirical consequences and extensive simulations to investigate these issues from a HVG methodological perspective. After carefully accounting for these methodological aspects, the HVG analysis reveals that the river runoff dataset shows indeed complex behavior that appears to stem from a superposition of short-term correlated noise and “long-tailed behaviour,” i.e., highly connected nodes. Moreover, the construction of a dam along a river tends to increase short-term correlations in runoff series. In summary, the present study illustrates the (often substantial) effects of methodological and data-preprocessing choices for the interpretation of river runoff dynamics in the HVG framework and its general applicability for real-world time series.Fil: Lange, Holger. Norwegian Institute of Bioeconomy Research; NoruegaFil: Sippel, Sebastian. Norwegian Institute of Bioeconomy Research; NoruegaFil: Rosso, Osvaldo Aníbal. Instituto Universidad Escuela de Medicina del Hospital Italiano; Argentina. Universidad de Los Andes; Chile. Universidade Federal de Alagoas; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
The Logistical Challenges of the SpaceLiner Concept
The SpaceLiner concept developed at DLR combines extremely fast transport (90 minutes from Europe to Australia) with the experience of Space flight. As such it is different from the spaceflight which focuses exclusively on space tourism but it combines space tourism with for example business travel. The SpaceLiner is designed to carry 50 passengers in suborbital flight. The conceptual technical design presents some challenges which have already been partially investigated at DLR [1]. However, the overall commercial concept presents a number of different challenges. This paper will identify and describe the logistical challenges involved
Alone in the jungle
About 30 miles away from Dover, Rambo asks Liz for new shoes. He needs them to jump on a lorry, which is supposed to take him to his paradise. Last week, a friend of Rambo’s died when he tried to do the same thing. Rambo, wearing white forearm protectors, will not die, because he is the king of the universe. At least, that’s what Rambo believes. He also believes that he is about 12 years old, but he doesn’t know for sure. Only a few of the boys in the Calais Jungle know their actual age
Multimodal Gaze Stabilization of a Humanoid Robot based on Reafferences
Gaze stabilization is fundamental for humanoid robots. By stabilizing vision,
it enhances perception of the environment and keeps points of interest in the
field of view. In this contribution, a multimodal gaze stabilization combining
classic inverse kinematic control with vestibulo-ocular and optokinetic
reflexes is introduced. Inspired by neuroscience, it implements a forward model
that can modulate the reflexes based on the reafference principle. This
principle filters self-generated movements out of the reflexive feedback loop.
The versatility and effectiveness of this method are experimentally validated
on the Armar-III humanoid robot. It is first demonstrated that each
stabilization mechanism (inverse kinematics and reflexes) performs better than
the others as a function of the type of perturbation to be stabilized.
Furthermore, combining these three modalities by reafference provides a
universal gaze stabilizer which can handle any kind of perturbation
Publications of the Jet Propulsion Laboratory, July 1961 through June 1962
Jpl bibliography on space science, 1961-196
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