57 research outputs found
Asymptotic goodness-of-fit tests for the Palm mark distribution of stationary point processes with correlated marks
We consider spatially homogeneous marked point patterns in an unboundedly
expanding convex sampling window. Our main objective is to identify the
distribution of the typical mark by constructing an asymptotic
-goodness-of-fit test. The corresponding test statistic is based on a
natural empirical version of the Palm mark distribution and a smoothed
covariance estimator which turns out to be mean square consistent. Our approach
does not require independent marks and allows dependences between the mark
field and the point pattern. Instead we impose a suitable -mixing
condition on the underlying stationary marked point process which can be
checked for a number of Poisson-based models and, in particular, in the case of
geostatistical marking. In order to study test performance, our test approach
is applied to detect anisotropy of specific Boolean models.Comment: Published in at http://dx.doi.org/10.3150/13-BEJ523 the Bernoulli
(http://isi.cbs.nl/bernoulli/) by the International Statistical
Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm). arXiv admin
note: substantial text overlap with arXiv:1205.504
Transient Dynamic System Behavior of Pressure Actuated Cellular Structures in a Morphing Wing
High aspect ratio aircraft have a significantly reduced induced drag, but have only limited installation space for control surfaces near the wingtip. This paper describes a multidisciplinary design methodology for a morphing aileron that is based on pressure-actuated cellular structures (PACS). The focus of this work is on the transient dynamic system behavior of the multi-functional aileron. Decisive design aspects are the actuation speed, the resistance against external loads, and constraints preparing for a future wind tunnel test. The structural stiffness under varying aerodynamic loads is examined while using a reduced-order truss model and a high-fidelity finite element analysis. The simulations of the internal flow investigate the transient pressurization process that limits the dynamic actuator response. The authors present a reduced-order model based on the Pseudo Bond Graph methodology enabling time-efficient flow simulation and compare the results to computational fluid dynamic simulations. The findings of this work demonstrate high structural resistance against external forces and the feasibility of high actuation speeds over the entire operating envelope. Future research will incorporate the fluidâstructure interaction and the assessment of load alleviation capability
Direct prediction of site-specific lime requirement of arable fields using the base neutralizing capacity and a multi-sensor platform for on-the-go soil mapping
Liming agricultural fields is necessary for counteracting soil acidity and is one of the oldest operations in soil fertility management. However, the best management practice for liming in Germany only insufficiently considers within-field soil variability. Thus, a site-specific variable rate liming strategy was developed and tested on nine agricultural fields in a quaternary landscape of north-east Germany. It is based on the use of a proximal soil sensing module using potentiometric, geoelectric and optical sensors that have been found to be proxies for soil pH, texture and soil organic matter (SOM), which are the most relevant lime requirement (LR) affecting soil parameters. These were compared to laboratory LR analysis of reference soil samples using the soilâs base neutralizing capacity (BNC). Sensor data fusion utilizing stepwise multi-variate linear regression (MLR) analysis was used to predict BNC-based LR (LRBNC) for each field. The MLR models achieved high adjusted R2 values between 0.70 and 0.91 and low RMSE values from 65 to 204 kg CaCO3 haâ1. In comparison to univariate modeling, MLR models improved prediction by 3 to 27% with 9% improvement on average. The relative importance of covariates in the field-specific prediction models were quantified by computing standardized regression coefficients (SRC). The importance of covariates varied between fields, which emphasizes the necessity of a field-specific calibration of proximal sensor data. However, soil pH was the most important parameter for LR determination of the soils studied. Geostatistical semivariance analysis revealed differences between fields in the spatial variability of LRBNC. The sill-to-range ratio (SRR) was used to quantify and compare spatial LRBNC variability of the nine test fields. Finally, high resolution LR maps were generated. The BNC-based LR method also produces negative LR values for soil samples with pH values above which lime is required. Hence, the LR maps additionally provide an estimate on the quantity of chemically acidifying fertilizers that can be applied to obtain an optimal soil pH value
A minimal model of peptide binding predicts ensemble properties of serum antibodies
<p/> <p>Background</p> <p>The importance of peptide microarrays as a tool for serological diagnostics has strongly increased over the last decade. However, interpretation of the binding signals is still hampered by our limited understanding of the technology. This is in particular true for arrays probed with antibody mixtures of unknown complexity, such as sera. To gain insight into how signals depend on peptide amino acid sequences, we probed random-sequence peptide microarrays with sera of healthy and infected mice. We analyzed the resulting antibody binding profiles with regression methods and formulated a minimal model to explain our findings.</p> <p>Results</p> <p>Multivariate regression analysis relating peptide sequence to measured signals led to the definition of amino acid-associated weights. Although these weights do not contain information on amino acid position, they predict up to 40-50% of the binding profiles' variation. Mathematical modeling shows that this position-independent ansatz is only adequate for highly diverse random antibody mixtures which are not dominated by a few antibodies. Experimental results suggest that sera from healthy individuals correspond to that case, in contrast to sera of infected ones.</p> <p>Conclusions</p> <p>Our results indicate that position-independent amino acid-associated weights predict linear epitope binding of antibody mixtures only if the mixture is random, highly diverse, and contains no dominant antibodies. The discovered ensemble property is an important step towards an understanding of peptide-array serum-antibody binding profiles. It has implications for both serological diagnostics and B cell epitope mapping.</p
Base Neutralizing Capacity of Agricultural Soils in a Quaternary Landscape of North-East Germany and Its Relationship to Best Management Practices in Lime Requirement Determination
Despite being a natural soil-forming process, soil acidification is a major agronomic challenge under humid climate conditions, as soil acidity influences several yield-relevant soil properties. It can be counterbalanced by the regular application of agricultural lime to maintain or re-establish soil fertility and to optimize plant growth and yield. To avoid underdose as well as overdose, lime rates need to be calculated carefully. The lime rate should be determined by the optimum soil pH (target pH) and the response of the soil to lime, which is described by the base neutralizing capacity (BNC). Several methods exist to determine the lime requirement (LR) to raise the soil pH to its optimum. They range from extremely time-consuming equilibration methods, which mimic the natural processes in the soil, to quick tests, which rely on some approximations and are designed to provide farmers with timely and cost-efficient data. Due to the higher analytical efforts, only limited information is available on the real BNC of particular soils. In the present paper, we report the BNC of 420 topsoil samples from Central Europe (north-east Germany), developed on sediments from the last ice age 10,000 years ago under Holocene conditions. These soils are predominantly sandy and low in humus, but they exhibit a huge spatial variability in soil properties on a small scale. The BNC was determined by adding various concentrations of Ca(OH)2 and fitting an exponential model to derive a titration curve for each sample. The coefficients of the BNC titration curve were well correlated with soil properties affecting soil acidity and pH buffer capacity, i.e., pH, soil texture and soil organic matter (SOM). From the BNC model, the LRs (LRBNC) were derived and compared with LRVDLUFA based on the standard protocol in Germany as established by the Association of German Agricultural Analytic and Research Institutes (VDLUFA). The LRBNC and LRVDLUFA correlated well but the LRVDLUFA were generally by approximately one order of magnitude higher. This is partly due to the VDLUFA concept to recommend a maintenance or conservation liming, even though the pH value is in the optimum range, to keep it there until the next lime application during the following rotation. Furthermore, the VDLUFA method was primarily developed from field experiments where natural soil acidification and management practices depressed the effect of lime treatment. The BNC method, on the other hand, is solely based on laboratory analysis with standardized soil samples. This indicates the demand for further research to develop a sound scientific algorithm that complements LRBNC with realistic values of annual Ca2+ removal and acidification by natural processes and N fertilization
Experimental investigation of high-power laser irradiation of missile materials in subsonic and supersonic flows
The technology of missiles and of their countermeasures is evolving continuously. High-power lasers are an option to encounter these threats. In order to understand their potential in such a scenario, it is vital to investigate the laser effects in the presence of a corresponding aerodynamic environment. Thus, experimental and numerical investigations were conducted cooperatively by Fraunhofer Ernst-Mach-Institut and the supersonic and hypersonic technologies department of DLR. An ytterbium fiber laser system was installed at the supersonic wind tunnel VMK. The laboratory was fit to meet necessary laser safety requirements. Combined subsonic and supersonic flow and high-power laser experiments with flow velocities up to a Mach number of three and a laser power up to 10 kW were realized. Two kind of tests were performed, focusing on laser beam distortion through aero-optical effects and on high-power laser effects, respectively. The interaction effects between aerodynamics, laser radiation and irradiated targets were studied on flat-plates as well as cylindrical and radome targets, simulating generic missile design. Irradiated objects consisted of steel, aluminum, carbon-fiber-reinforced polymer and the ceramic-based composite WHIPOX. While beam distortions were studied with a wavefront sensor, damaging processes were investigated by measuring the perforation time of the targets, as well as via high-speed imaging, thermography as well as Schlieren imaging. Numerical three-dimensional, steady, and uncoupled simulations were performed. The data indicated complex interactions between material, laser beam, and aerodynamics. This investigation can be used as an initial basis for further analysis of laser-material-aerodynamic interactions with respect to missile defense
Guidelines for precise lime management based on high-resolution soil pH, texture and SOM maps generated from proximal soil sensing data
Soil acidification is caused by natural paedogenetic processes and anthropogenic impacts but can be counteracted by regular lime application. Although sensors and applicators for variable-rate liming (VRL) exist, there are no established strategies for using these tools or helping to implement VRL in practice. Therefore, this study aimed to provide guidelines for site-specific liming based on proximal soil sensing. First, high-resolution soil maps of the liming-relevant indicators (pH, soil texture and soil organic matter content) were generated using on-the-go sensors. The soil acidity was predicted by two ion-selective antimony electrodes (RMSEpH: 0.37); the soil texture was predicted by a combination of apparent electrical resistivity measurements and natural soil-borne gamma emissions (RMSEclay: 0.046 kg kgâ1); and the soil organic matter (SOM) status was predicted by a combination of red (660 nm) and near-infrared (NIR, 970 nm) optical reflection measurements (RMSESOM: 6.4 g kgâ1). Second, to address the high within-field soil variability (pH varied by 2.9 units, clay content by 0.44 kg kgâ1 and SOM by 5.5 g kgâ1), a well-established empirical lime recommendation algorithm that represents the best management practices for liming in Germany was adapted, and the lime requirements (LRs) were determined. The generated workflow was applied to a 25.6 ha test field in north-eastern Germany, and the variable LR was compared to the conventional uniform LR. The comparison showed that under the uniform liming approach, 63% of the field would be over-fertilized by approximately 12 t of lime, 6% would receive approximately 6 t too little lime and 31% would still be adequately limed. © 2020, The Author(s)
Meeresatlas: Daten und Fakten ĂŒber unseren Umgang mit dem Ozean
Ohne das Meer gĂ€be es kein Leben auf unserem Planeten. Es regelt weitgehend das Klima, gibt uns Nahrung und liefert Energie. DarĂŒber hinaus ist es ein wichtiger Verkehrsweg, ein Erholungsraum und ein Quell Ă€sthetischen VergnĂŒgens. Aber das Meer steht unter Stress, denn das alte Prinzip von der âFreiheit der Meereâ hat zu Ăberfischung, Artenverlust und einer immensen Verschmutzung der Ozeane gefĂŒhrt.
Deshalb muss der Umgang mit dem Meer auf nachhaltige und gerechte Grundlagen gestellt werden. Der Meeresatlas 2017 liefert dazu die Daten, Fakten und ZusammenhĂ€nge. Er zeigt in zahlreichen BeitrĂ€gen und ĂŒber 50 Grafiken, in welch schlechtem Zustand sich die Weltmeere befinden, warum das so ist und was man tun muss, um die Situation der Ozeane zu verbessern
Navigating the Future V: Marine Science for a Sustainable Future
Navigating the Future is a publication series produced by the European Marine Board providing future
perspectives on marine science and technology in Europe. Navigating the Future V (NFV) highlights new
knowledge obtained since Navigating the Future IV1 (2013). It is set within the framework of the 2015
Paris Agreement2 and builds on the scientific basis and recommendations of the IPCC reports3. NFV gives
recommendations on the science required during the next decade to deliver the ocean we need to support
a sustainable future. This will be important for the United Nations Decade of Ocean Science for Sustainable
Development4 (2021 â 2030), the implementation of the UN Sustainable Development Goals5 and the
European Commissionâs next framework programme, Horizon Europe6 (2021 - 2027). There is a growing need
to strengthen the links between marine science, society and policy since we cannot properly manage what
we do not know.
In recent years, the ocean and seas have received new prominence in international agendas. To secure a
safe planet a priority is the management of the ocean as a âcommon good for humanityâ, which requires
smarter observations to assess of the state of the ocean and predictions about how it may change in the
future. The ocean is a three-dimensional space that needs to be managed over time (thus four-dimensional),
and there is a need for management and conservation practices that integrate the structure and function
of marine ecosystems into these four dimensions (Chapter 2). This includes understanding the dynamic
spatial and temporal interplay between ocean physics, chemistry and biology. Multiple stressors including
climate change, pollution and over-fishing affect the ocean and we need to better understand and predict
their interactions and identify tipping points to decide on management priorities (Chapter 3). This should
integrate our understanding of land-ocean-atmosphere processes and approaches to reducing impacts. An
improved science base is also needed to help predict and minimize the impact of extreme events such as
storm surges, heat waves, dynamic sea-floor processes and tsunamis (Chapter 4). New technologies, data
handling and modelling approaches will help us to observe, understand and manage our use of the fourdimensional
ocean and the effect of multiple stressors (Chapter 5).
Addressing these issues requires a strategic, collective and holistic approach and we need to build a
community of sustainability scientists that are able to provide evidence-based support to policy makers
within the context of major societal challenges (Chapter 6). We outline new frontiers, knowledge gaps and
recommendations needed to manage the ocean as a common good and to develop solutions for a sustainable
future (Chapter 7). The governance of sustainability should be at the core of the marine research agenda
through co-production and collaboration with stakeholders to identify priorities. There is need for a fully
integrated scientific assessment of resilience strategies, associated trade-offs and underlying ethical concepts
for the ocean, which should be incorporated into decision support frameworks that involve stakeholders from
the outset. To allow the collection, processing and access to all data, a key priority is the development of a
business model that ensures the long-term economic sustainability of ocean observations
- âŠ