Numerical investigation into the application of response conditioned waves for long-term nonlinear fatigue analyses of rigid hulls     

Ingo Drummen  MingKang Wu  Miroslaw Lech Kaminski  Torgeir Moan 《Ocean Engineering》2009,36(15-16):1208-1216

Previous studies of response conditioned wave methods have been focused on their applicability to the prediction of extreme nonlinear wave-induced load effects. The results showed that theses methods can be used to accurately and efficiently predict the nonlinear short-term probability distributions for rigid hull responses. This has led us to investigate how response conditioned wave methods can be used for long-term nonlinear fatigue analyses, and with which accuracy this can be done. In this paper we present the results from our investigation. The studies were performed using a container vessel with a length between perpendiculars of 281 m. Calculations were done with a nonlinear strip theory method in which the hull of the vessel was assumed to be rigid. The most likely response wave (MLRW) method was used to condition the waves. Only head seas were considered. We found that the MLRW method under-predicted the long-term fatigue damage by 3%. The method, however, required a simulation time that was approximately three orders of magnitude less than that required for a conventional long-term nonlinear analysis based on random irregular waves. A preliminary investigation showed that due to lacking springing and whipping contributions the MLRW method under-predicted the fatigue damage for a flexible hull by approximately 50%. Several comments about a more accurate extension of the proposed method to flexible hulls are included.  相似文献   

Improved representation of topographic effects by a vertical adaptive grid in Vector-Ocean-Model (VOM). Part II: Simulations in unstructured adaptive grids     

Jan O. Backhaus  Ingo Harms  Udo Hübner 《Ocean Modelling》2008,22(3-4):128-145

A static adaptive grid approximates the topography and defines the vertical resolution in Vector-Ocean-Model (VOM). The adaptation to topography creates unstructured grids, which are organised in a one-dimensional vector by column-wise storage of only wet cells. The model’s name reflects this data structure. The intention of VOM is better resolving flow and stratification near topographic boundaries in Z-coordinates. This is the second part of a publication that describes the generation of adaptive grids (part I), and simulations with VOM in unstructured grids (this part). Adaptive grids generated for a synthetic topography in part I include shelf, continental slope, and ocean. Three of those grids are here utilised in upwelling simulations. Under the same forcing increased vertical resolution at seabed and slopes yields a significant increase in flow energy as compared to coarser grids. Results allow explaining the surface intensification of a continental slope jet by vertical displacements of water masses in the seabed Ekman layer. Results in unstructured grids are almost identical to reference simulations in equidistant grids where the respective smallest grid size of unstructured grids was used. Negative effects of grids on predicted flow and stratification are absent also over particularly rough topography, as demonstrated by using vertical velocity as most sensitive indicator. In a further simulation an overflow governed by the advection of water mass properties is presented to demonstrate the conservation properties of the model. After 5 months of simulation the predicted domain average temperature deviated by 10⁻⁸ from the initial temperature field. Compared to equidistant grids the advection/diffusion scheme looses about one order of magnitude in accuracy when used in an unstructured grid. The results of VOM, being defined in Z-coordinates, are void of coordinate transformation errors. In an arbitrary topography unforced zero-flow remains quiescent in a stratification that only varies in the vertical. VOM due to its depth-independent vertical resolution appears particularly suitable for simulations of ocean-shelf exchange.  相似文献   

Cosmogenic production rates and recoil loss effects in micrometeorites and interplanetary dust particles     

Reto Trappitsch  Ingo Leya 《Meteoritics & planetary science》2013,48(2):195-210

We present a purely physical model to determine cosmogenic production rates for noble gases and radionuclides in micrometeorites (MMs) and interplanetary dust particles (IDPs) by solar cosmic‐rays (SCR) and galactic cosmic‐rays (GCR) fully considering recoil loss effects. Our model is based on various nuclear model codes to calculate recoil cross sections, recoil ranges, and finally the percentages of the cosmogenic nuclides that are lost as a function of grain size, chemical composition of the grain, and the spectral distribution of the projectiles. The main advantage of our new model compared with earlier approaches is that we consider the entire SCR particle spectrum up to 240 MeV and not only single energy points. Recoil losses for GCR‐produced nuclides are assumed to be equal to recoil losses for SCR‐produced nuclides. Combining the model predictions with Poynting‐Robertson orbital lifetimes, we calculate cosmic‐ray exposure ages for recently studied MMs, cosmic spherules, and IDPs. The ages for MMs and the cosmic‐spherule are in the range <2.2–233 Ma, which corresponds, according to the Poynting‐Robertson drag, to orbital distances in the range 4.0–34 AU. For two IDPs, we determine exposure ages of longer than 900 Ma, which corresponds to orbital distances larger than 150 AU. The orbital distance in the range 4–6 AU for one MM and the cosmic spherule indicate an origin either in the asteroid belt or release from comets coming either from the Kuiper Belt or the Oort Cloud. Three of the studied MMs have orbital distances in the range 23–34 AU, clearly indicating a cometary origin, either from short‐period comets from the Kuiper Belt or from the Oort Cloud. The two IDPs have orbital distances of more than 150 AU, indicating an origin from Oort Cloud comets.  相似文献   

Erratum to: Eight-hundred years of summer temperature variations in the southeast of the Iberian Peninsula reconstructed from tree rings     

Isabel Dorado Liñán  Eduardo Zorita  Jesús Fidel González-Rouco  Ingo Heinrich  Filipe Campelo  Elena Muntán  Laia Andreu-Hayles  Emilia Gutiérrez 《Climate Dynamics》2015,44(7-8):2329-2329

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An overview of the performance of CMIP6 models in the tropical Atlantic: mean state,variability, and remote impacts     

Richter  Ingo  Tokinaga  Hiroki 《Climate Dynamics》2020,55(9-10):2579-2601

General circulation models of the Coupled Model Intercomparison Project Phase 6 (CMIP6) are examined with respect to their ability to simulate the mean state and variability of the tropical Atlantic and its linkage to the tropical Pacific. While, on average, mean state biases have improved little, relative to the previous intercomparison (CMIP5), there are now a few models with very small biases. In particular the equatorial Atlantic warm SST and westerly wind biases are mostly eliminated in these models. Furthermore, interannual variability in the equatorial and subtropical Atlantic is quite realistic in a number of CMIP6 models, which suggests that they should be useful tools for understanding and predicting variability patterns. The evolution of equatorial Atlantic biases follows the same pattern as in previous model generations, with westerly wind biases during boreal spring preceding warm sea-surface temperature (SST) biases in the east during boreal summer. A substantial portion of the westerly wind bias exists already in atmosphere-only simulations forced with observed SST, suggesting an atmospheric origin. While variability is relatively realistic in many models, SSTs seem less responsive to wind forcing than observed, both on the equator and in the subtropics, possibly due to an excessively deep mixed layer originating in the oceanic component. Thus models with realistic SST amplitude tend to have excessive wind amplitude. The models with the smallest mean state biases all have relatively high resolution but there are also a few low-resolution models that perform similarly well, indicating that resolution is not the only way toward reducing tropical Atlantic biases. The results also show a relatively weak link between mean state biases and the quality of the simulated variability. The linkage to the tropical Pacific shows a wide range of behaviors across models, indicating the need for further model improvement.

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The common information platform for natural hazards in Switzerland     

Benedikt Heil  Ingo Petzold  Hans Romang  Josef Hess 《Natural Hazards》2014,70(3):1673-1687

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Noble gas studies in CAIs from CV3 chondrites: No evidence for primordial noble gases     

Nadia Vogel  Heinrich Baur  Addi Bischoff  Ingo Leya  Rainer Wieler 《Meteoritics & planetary science》2004,39(5):767-778

Abstract— Calcium‐aluminum‐rich inclusions (CAIs) were among the first solids in the solar system and were, similar to chondrules, created at very high temperatures. While in chondrules, trapped noble gases have recently been detected, the presence of trapped gases in CAIs is unclear but could have important implications for CAI formation and for early solar system evolution in general. To reassess this question, He, Ne, and Ar isotopes were measured in small, carefully separated and, thus, uncontaminated samples of CAIs from the CV3 chondrites Allende, Axtell, and Efremovka. The ²⁰Ne/²²Ne ratios of all CAIs studied here are <0.9, indicating the absence of trapped Ne as, e.g., Ne‐HL, Ne‐Q, or solar wind Ne. The ²¹Ne/²²Ne ratios range from 0.86 to 0.72, with fine‐grained, more altered CAIs usually showing lower values than coarse‐grained, less altered CAIs. This is attributed to variable amounts of cosmogenic Ne produced from Na‐rich alteration phases rather than to the presence of Ne‐G or Ne‐R (essentially pure ²²Ne) in the samples. Our interpretation is supported by model calculations of the isotopic composition of cosmogenic Ne in minerals common in CAIs. The ³⁶Ar/³⁸Ar ratios are between 0.7 and 4.8, with fine‐grained CAIs within one meteorite showing higher ratios than the coarse‐grained ones. This agrees with higher concentrations of cosmogenic ³⁶Ar produced by neutron capture on ³⁵Cl with subsequent β^?‐decay in finer‐grained, more altered, and thus, more Cl‐rich CAIs than in coarser‐grained, less altered ones. Although our data do not strictly contradict the presence of small amounts of Ne‐G, Ne‐R, or trapped Ar in the CAIs, our noble gas signatures are most simply explained by cosmogenic production, mainly from Na‐, Ca‐, and Cl‐rich minerals.  相似文献   

The EChO payload instrument – an overview     

Paul Eccleston  Bruce Swinyard  Marcel Tessenyi  Giovanna Tinetti  Ingo Waldmann  Marc Ferlet  Ranah Irshad  Tanya Lim  Kevin Middleton  Tom Bradshaw  Martin Crook  Tom Hunt  Berend Winter  Ian Bryson  Naidu Bezawada  William Taylor  Neil Bowles  Enzo Pascale  Gianluca Morgante  Emanuele Pace  Alberto Adriani  Jean-Michel Reess  Marc Ollivier  Roland Ottensamer  Mirek Rataj  Gonzalo Ramos Zapata  Jan-Rutger Schrader  Avri Selig  Kate Isaak  Martin Linder  Ludovic Puig 《Experimental Astronomy》2015,40(2-3):427-447

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MediaPark Köln,Germany — Urban planning vision becomes reality     

Utz Ingo Küpper Dr.  Brigitte Göttgens 《GeoJournal》1991,25(4):443-446

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On the origin of equatorial Atlantic biases in coupled general circulation models   总被引：8，自引：6，他引：2  

Ingo Richter  Shang-Ping Xie 《Climate Dynamics》2008,31(5):587-598

Many coupled ocean–atmosphere general circulation models (GCMs) suffer serious biases in the tropical Atlantic including a southward shift of the intertropical convergence zone (ITCZ) in the annual mean, a westerly bias in equatorial surface winds, and a failure to reproduce the eastern equatorial cold tongue in boreal summer. The present study examines an ensemble of coupled GCMs and their uncoupled atmospheric component to identify common sources of error. It is found that the westerly wind bias also exists in the atmospheric GCMs forced with observed sea surface temperature, but only in boreal spring. During this time sea-level pressure is anomalously high (low) in the western (eastern) equatorial Atlantic, which appears to be related to deficient (excessive) precipitation over tropical South America (Africa). In coupled simulations, this westerly bias leads to a deepening of the thermocline in the east, which prevents the equatorial cold tongue from developing in boreal summer. Thus reducing atmospheric model errors during boreal spring may lead to improved coupled simulations of tropical Atlantic climate.  相似文献