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This paper discusses the risks associated with an aerostat-supported stratospheric (unanchored) balloon mission equipped with a long vertical antenna and a very low frequency radio transmitter. The risks have been grouped into four main types and applicable mitigation methods have been presented to provide a sufficient level of safety and reliability to such a balloon mission. An experimental mission consistent with this analysis, based on the described theoretical VLF propagation approach, has been prepared and launched, and is operating at 14.2 kHz with a vertical antenna of a total length of 400 m and a total payload of max. 4 kg. The maximum altitude reached 29,164 m. The experiment's signal has been registered in numerous locations in Europe; the results are compared with numerical analysis employing a hypothesis of an apparent transmitting frequency decrease with the rise of the transmitter's altitude. The numerical analysis explains the behavior of the experimental signal and remains generally consistent with the hypothesis. [ABSTRACT FROM AUTHOR]

In recent years, thermal insulation filled masonry blocks have become widespread in Central-Europe. These blocks can satisfy thermal performance requirements without the need of additional insulation. However, these requirements in the building regulations only consider thermal, but neglect moisture aspects. This paper presents a comparative analysis of steady-state numerical conjugated heat- and moisture transport FEM simulations of masonry walls. The hygrothermal material properties of the insulation filled masonry blocks were measured in laboratory. In the paper, besides a wall section, a wall corner joint is presented, both modeled in 2D from complex building elements, such as insulation filled blocks, and were tested using different fillers (aerogel, expanded perlite, expanded polystyrene, mineral wool and PUR foam), respectively. Monthly variation of the fillers' thermal conductivity, thermal and moisture transmittance and effective water vapor diffusion resistance of the walls, as well as linear thermal and moisture transmittance of the wall corner joints were examined in details. A comparison between detailed and simplified modeling were also carried out. The evaluation of the results shows that there are noticeable differences in trends between thermal and moisture transmittances, latter show significantly greater variation and depends mainly on the hygrothermal behavior of the filler. Based on effective water vapor resistance factors, we showed that assuming the same vapor transmission properties for all type of filled masonry blocks is a mistake. [ABSTRACT FROM AUTHOR]

In this paper, requirements for a new aircraft designed for the regional market are presented. The design is mainly driven to fulfill the needs of the next-generation air transportation system. Today, Europe's major hubs have already reached the limit of their capacity. To facilitate the predicted growth rate of air transportation, smaller regional airports have to be integrated into the current airport network. To analyze the impact on the air transportation system, a numerical model is presented that allocates potential passengers from their place of origin to their most likely airport of choice. This passenger allocation model is used to predict future airport's growth rates and possible capacity shortages for given airport scenarios and helps to investigate the influence of the integration of new airports and a new aircraft concept into the current air transportation system. The simulation presented in this paper is based on the German airport network, but it can be easily adapted to any other national or international scenario. Requirements for an aircraft serving such smaller regional airports are directly derived from this simulation. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a 44-year (from 1958 to 2001) wave hindcast conducted for the North Atlantic, using a fine grid in the North East Atlantic coastal areas of Europe. The wind fields were obtained by a local area model that was applied in the areas adjacent to the European coasts, which was forced by the results of the NCEP reanalysis. While the NCEP results have a spatial distribution of 2° and a time step of 6 h the wind fields produced by the local area model have a spatial resolution of 0.5° and a time step of 1 h, which is important for accurate descriptions of the conditions in coastal areas and in rapidly changing storms. A version of the WAM model that allowed two-way nesting was adopted and calculations were made with nested grids allowing a fine resolution in the coastal areas of Europe. This paper includes the description of the set-up of the wave model and the validation performed vs. in-situ measurements so as to allow assessments of the quality of the data produced in this study. [Copyright &y& Elsevier]

Slip between layers, material properties of layers and geometric non-linearities largely dictate both the bearing capacity and the ductility of a composite beam. That is why the accuracy of their modelling in the numerical analysis of the composite beams is of utmost importance. In the present paper we present a new strain-based finite element model which considers these issues in a highly effective manner. Each layer of the beam is modelled by geometrically exact Reissner’s beam model. The layers are assumed to stay in the contact during deformation but the relative tangential displacement (slip) is possible. The non-linear load–slip law of the interface is considered. The formulation is found to be accurate, reliable and computationally time-effective. The further objective of the paper is an analysis of the buckling force of axially compressed layered wood columns, being simply supported, fixed–pinned or continuous. We compare the present numerical results with the analytical values of [Girhammar UA, Gopu VKA. Composite beam-columns with interlayer slip–exact analysis, J Struct Engng ASCE 1993;199(4):1265–82] and with the values, recommended by the European code for timber structures [Eurocode 5, Design of timber structures, Part 1-1: General rules and rules for buildings, 1993; ENV 1995-1-1]. The comparisons indicate that the European code for timber structures provides very conservative estimates for the buckling load. [Copyright &y& Elsevier]

An analysis of Bošković's early paper concerned with the polar light (aurora borealis) gives an insight into the validity of the mathematical method which the young Bošković applied to significant geophysical phenomena in order to comprehend their nature. Based on the given data, we have examined numerical results about the height of atmosphere and the heights of the auroras which were observed over Europe in 1726 and in 1737. In his text there is not a single mathematical formula. Following his instructions we have derived a formula which may be used to determine the distance of an aurora by observing it from one station. For the assumed aurora model, his method is applicable. We find that described ideas on the physical cause of aurora, conceived in a fluid coming from the sun, have elements of modern knowledge. [ABSTRACT FROM AUTHOR]

In this paper, we present a highly efficient approach for numerically solving the Black–Scholes equation in order to price European and American basket options. Therefore, hardware features of contemporary high performance computer architectures such as non-uniform memory access and hardware-threading are exploited by a hybrid parallelization using MPI and OpenMP which is able to drastically reduce the computing time. In this way, we achieve very good speed-ups and are able to price baskets with up to six underlyings. Our approach is based on a sparse grid discretization with finite elements and makes use of a sophisticated adaption. The resulting linear system is solved by a conjugate gradient method that uses a parallel operator for applying the system matrix implicitly. Since we exploit all levels of the operator's parallelism, we are able to benefit from the compute power of more than 100 cores. Several numerical examples as well as an analysis of the performance for different computer architectures are provided. [ABSTRACT FROM PUBLISHER]

Abstract: During the eruption of Eyjafjallajökull on Iceland in April/May 2010, air traffic over Europe was repeatedly interrupted because of volcanic ash in the atmosphere. This completely unusual situation in Europe leads to the demand of improved crisis management, e.g. European wide regulations of volcanic ash thresholds and improved ash dispersion forecasts. However, the quality of the forecast of fine volcanic ash concentrations in the atmosphere depends to a great extent on a realistic description of the erupted mass flux of fine ash particles, which is rather uncertain. Numerous aerosol measurements (ground based and satellite remote sensing, and in-situ measurements) all over Europe tracked the volcanic ash clouds during the eruption of Eyjafjallajökull offering the possibility for an interdisciplinary effort between volcanologists and aerosol researchers to analyse the release and dispersion of fine volcanic ash in order to better understand the needs for realistic volcanic ash forecasts. In this introductory paper, we provide a general introduction into magma fragmentation processes during explosive volcanic eruptions, describe the evolution of the eruption of Eyjafjallajökull, present the possibilities of ground based in-situ and remote measurements and numerical model studies of volcanic ash and summarise open questions and future directions. [Copyright &y& Elsevier]

Abstract: Jack arch masonry slab, developed in the post-industrial revolution Britain has been used extensively to floor and roof industrial and residential buildings in many parts of the world. It is still in use in parts of Europe, the Middle East and Indian subcontinent. Collapse of a large number of these composite slabs during past earthquakes, including those belonging to some buildings of historic importance, has pointed out the weakness of this type of flooring to seismic loading. It has also highlighted the need for developing appropriate retrofitting schemes. Two different retrofitting methods are currently in use. One method uses a thin reinforced concrete layer over the slab to provide integrity and the necessary strength. Another method utilizes transverse beams to form a steel grid with the main beams to achieve the same objectives. In this paper, out-of-plane pushover tests are first conducted on a number of full-scale ordinary and retrofitted jack arch slabs. Results of the tests are then used to compare the strength capacity and other seismic performance parameters of the slabs including; ductility and the behaviour factor. Numerical analyses are also carried out in support of the experimental investigation. It is concluded that the steel grid method of retrofitting, in addition to being easier and faster to perform and much less costly, addresses all the strength and performance requirements of the slab, whereas, the concrete layer method, though effective in increasing the strength, considerably increases the weight of the slab, which, in turn, may increase strength demand on other structural elements. The benefits of using the concrete layer in improving the seismic performance are also less than those of the steel grid method. [Copyright &y& Elsevier]

Abstract: In Europe, the preferential tax treatment of company cars implies that many employees receive a company car as part of their compensation package. In this paper, we consider a model in which wages and the decision whether or not to provide a company car are the result of direct negotiation between employer and employee. Using this framework, we theoretically and numerically study first- and second-best optimal tax policies on labour and transport markets, focusing on the role of the tax treatment of company cars. We obtain the following results. First, higher labour taxes and a more favourable tax treatment of company cars raise the fraction employees that receives a company car; congestion and congestion tolls reduce it. Second, in countries that provide large implicit subsidies to company cars, eliminating the preferential tax treatment of company cars may be an imperfect but quite effective substitute for currently unavailable congestion tolls. The numerical illustration, calibrated using Belgian data, suggests that it yields about half the welfare gain attainable through optimal congestion taxes. Third, the favourable tax treatment of company cars justifies large public transport subsidies; the numerical results are consistent with zero public transport fares. Finally, we find that earlier models that ignored the preferential tax treatment of company cars may have substantially underestimated optimal congestion tolls in Europe. The numerical illustration suggests that about one third of the optimal congestion toll we obtain can be attributed to the current tax treatment of company cars. [Copyright &y& Elsevier]

Abstract: The reliable estimation of buildings energy needs for cooling is a crucial issue in the implementation of the EPB Directive 2010/31/EU (formerly 2002/91/EC), especially in central and southern Europe climates. On this purpose one of the main topics is to predict the behavior of the opaque envelope subjected to variable boundary conditions. The EN ISO 13786:2007 technical standard assumes sinusoidal boundary conditions and introduces dynamic thermal characteristics. The aim of this paper is to assess the deviation arising by the use of different approaches for the calculation of the dynamic thermal characteristics of an opaque envelope element under periodic non sinusoidal boundary conditions. The EN ISO 13786 procedure has been firstly applied by decomposing the external forcing temperature by means of the Fast Fourier Transform (FFT) analysis. A comparison with different approaches, such as Finite Difference Methods (FDM) and Transfer Function Methods (TFM), has been carried out. The predictions of the EN ISO 13786 with a sinusoidal forcing temperature (i.e., standard approach) have also been assessed, comparing the results to the ones obtained through the FFT analysis. Furthermore, corrections to the periodic thermal transmittance and to the time shift have been proposed, in order to improve the explicative worth of those parameters. [Copyright &y& Elsevier]

Abstract: A review by Hollander et al. (in preparation), discusses the relative potentials, advantages and shortcomings of spatial and non spatial models of chemical fate, highlighting that spatially explicit models may be needed for specific purposes. The present paper reviews the state of the art in spatially explicit chemical fate and transport modeling in Europe. We summarize the three main approaches currently adopted in spatially explicit modeling, namely (1) multiple box models, (2) numerical solutions of simultaneous advection–dispersion equations (ADE) in air, soil and water, and (3) the development of meta-models. As all three approaches experience limitations, we describe in further detail geographic information system (GIS)-based modeling as an alternative approach allowing a simple, yet spatially explicit description of chemical fate. We review the input data needed, and the options available for their retrieval at the European scale. We also discuss the importance of, and limitations in model evaluation. We observe that the high uncertainty in chemical emissions and physico-chemical behavior in the environment make realistic simulations difficult to obtain. Therefore we envisage a shift in model use from process simulation to hypothesis testing, in which explaining the discrepancies between observed and computed chemical concentrations in the environment takes importance over prediction per se. This shift may take advantage of using simple models in GIS with residual uses of complex models for detailed studies. It also calls for tighter joint interpretation of models and spatially distributed monitoring datasets, and more refined spatial representation of environmental drivers such as landscape and climate variables, and better emission estimates. In summary, we conclude that the problem is not “how to compute” (i.e. emphasis on numerical methods, spatial/temporal discretization, quantitative uncertainty and sensitivity analysis…) but “what to compute” (i.e. emphasis on spatial distribution of emissions, and the depiction of appropriate spatial patterns of environmental drivers). [Copyright &y& Elsevier]

The extreme dependency score EDS has been recently proposed as a nonvanishing measure of skill to verify predictions of rare events. An idealized example is employed to investigate the properties of the EDS when the probability of the event happening is small, as is the case for rare events. The paper warns about the nondependency of EDS on the false alarms and the correct rejections when the sample size is fixed, which encourages hedging. Thus, the EDS should not be the sole score used to assess a models performance on forecasting rare events. The dependency of the EDS on the event probability base rate is also analysed. It is shown that the EDS can be written as a function of the base rate and the hit rate, and that only in a very particular condition the score is independent of the event probability. Therefore, when comparing forecasts skills in terms of the EDS, special attention has to be paid to separate the variations in skill from the variations of the probability that the event happens over time.The score is used to assess the performance of the ECMWF deterministic precipitation forecast over Europe for different forecast ranges and precipitation thresholds. Verification of precipitation forecasts in terms of EDS, combined with an assessment of the false alarm rate, shows a clear improvement of the ECMWF deterministic forecast for precipitation of rare events i.e. large rainfall amounts. Copyright © 2009 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Abstract: This paper addresses the design of container liner shipping networks taking into consideration container management issues including empty container repositioning. We examine two typical service networks with different ship sizes: multi-port calling by conventional ship size and hub-and-spoke by mega-ship. The entire solution process is performed in two phases: the service network design and container distribution. A wide variety of numerical experiments are conducted for the Asia–Europe and Asia–North America trade lanes. In most scenarios the multi-port calling is superior in terms of total cost, while the hub-and-spoke is more advantageous in the European trade for a costly shipping company. [Copyright &y& Elsevier]

Abstract: The sediment transport processes in the south-western Baltic Sea are predicted by means of a numerical model in the project DYNAS. There are two sediment parameters that influence the results of modelling remarkably: critical shear stress velocity and bottom roughness. This paper presents the way how to parameterise these factors and extrapolate them into the investigation area. The critical shear stress velocity is parameterised basing on grain size data, combining approximations after Hjulström [Hjulström, F., 1935: Studies in the morphological activity of rivers as illustrated by the river Fyris. Geological Institution of University of Uppsala: Bulletin (25): 221–528.], Shields [Shields, A., 1936: Anwendung der Ähnlichkeits-Mechanik und der Turbulenzforschung auf die Geschiebebewegung. Mitteilungen der Preussischen Versuchsanstalt für Wasserbau und Schiffahrt (26): 26 pp.] and Bohling [Bohling, B., 2003: Untersuchungen zur Mobilität natürlicher und anthropogener Sedimente in der Mecklenburger Bucht. unpublished doctoral thesis, Mathematisch-Naturwissenschaftliche Fakultät, Ernst-Moritz-Arndt-Universität Greifswald/Germany, 156 pp.]. The roughness length, in the case of absence of macro zoo-benthos and their structures, is parameterised basing on grain size too employing Soulsby [Soulsby, R.L., 1997: Dynamics of Marine Sands: a Manual for Practical Applications. London, Thomas Telford Publications. 249 pp.], Nielsen [Nielsen, P., 1983: Analytical determination of nearshore wave height variation due to refraction shoaling and friction. Coastal Engineering 7, 233–251.] and Yalin [Yalin, M.S., 1977: Mechanics of Sediment Transport. Pergamon Press, New York. 298 pp.]. No equivalent simple parameterisations for biologically caused bed roughness exist. Here, findings of Friedrichs [Friedrichs, M., 2004: Flow-induced effects of macro zoo-benthic structures on the near-bed sediment transport. Dissertation, Universität Rostock, 80 S.] and estimations by the DYNAS biologists group were combined in order to derive roughness lengths from abundance measurements of four previously selected key species which represent the originators of the dominating benthic structures at the sea floor in the south-western Baltic Sea. Critical shear stress velocity and bed roughness are known at few sample sites only. They were extrapolated into the larger investigation area using a proxy-target concept. The mean near bottom milieu (bathymetry, median grain size, salinity, oxygen) which was derived using results from numerical modelling serves as the proxy. Since the milieu parameters are measured at the sampling sites for which the target parameters have been determined, a combined hierarchical and supervised classification was employed to transfer the local knowledge into the unknown investigation area. [Copyright &y& Elsevier]

Lightweight roof and wall structural systems are widely used for cladding of steel portal frames. It is a well-known fact, that assembled systems of profiled sheeting and purlins show significant stiffness to in-plane loads, which action is referred to as stressed skin effect. This research aimed to investigate the influencing parameters of stressed skin effect in those nonstandard diaphragm constructions, in which seam fasteners are omitted. The focus of this paper is on the results of an experimental test programme, that investigated the stiffness of nonstandard, 3.00 × 3.00 m sized diaphragm configurations for in-plane static load. The experimental results are compared against analytical results derived from calculated shear flexibilities according to current ECCS formulae. Upon experimental test results, a verified and validated numerical model is developed, and the range of experimental tests is extended by numerical simulations. The conclusions of numerical analyses demonstrated, that the effect of purlin section height and thickness is not followed by current ECCS provisions. The intended purpose of the research is to develop the current ECCS stressed skin design formulae to incorporate nonstandard diaphragm constructions, which are commonly used in industrial practice in Europe. The innovative feature of formulae improvement is to comprise the effect of those parameters, which are influencing shear flexibility and are not addressed in the current ECCS design methodology. Upon experimental, analytical and numerical results a modification is presented to current formulae of shear flexibility, which gives a better approach in nonstandard cases. • Experimental panel test series was conducted in order to examine the stiffening effect of commonly installed diaphragm configurations. • The main objective of the research is to examine nonstandard diaphragm constructions, in which seam fasteners are omitted. • To date no international study was performed to examine the stiffening effect of nonstandard steel diaphragms. • Upon experimental results a FE model was developed and verified, and an extended parametric study was carried out. • Based on these results a proposal is made in order to amend current ECCS formulae to incorporate nonstandard diaphragms. [ABSTRACT FROM AUTHOR]