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• A novel approach for regional ionosphere grid model with high spatial-temporal resolution is suggested. • The results of the new model is analyzed at different disturb geomagnetic and solar conditions. • A comparative analysis between the results of new model, GIM, NeQuick and GPS-TEC is made. In this paper, a novel approach based on C1 finite element (FE) interpolation is used to construct a regional ionospheric grid model (RIGM) with high spatio-temporal resolution over Europe. The spatial resolution of the new model is 0.50 for a longitude and latitude and a temporal resolution is 15 min. Observations of 38 GPS stations at different days and seasons with different geomagnetic and solar activity conditions are used to evaluate the new method. All stations are used to discretize the whole domain of the problem into separate triangular patches using a Delaunay triangulation algorithm. In this case, GPS stations would be the vertices of the triangular patches. Also, the position of stations in sun-fixed coordinate system with coordinates of latitude and longitude are chosen in order to consider the temporal variations of vertical total electron content (VTEC). To model the behavior of VTEC in each triangular patch, a particular shape function is defined which is fitted to VTEC values at three vertices of each triangle while it satisfies C1 continuity of VTEC at the common edges of the adjacent triangles. The results of the new model are compared with the VTEC of GPS at 4 control stations as well as global ionosphere map (GIM) and NeQuick models. Statistical parameters, including correlation coefficient, root mean square error (RMSE), standard deviation and dVTEC = |VTEC GPS - VTEC model | have been used to evaluate the error of the models. In low geomagnetic activity (KP < 4), the average RMSE at 4 control stations for FE, GIM and NeQuick models are 0.89, 1.05 and 6.42 TECU, respectively, while in the high geomagnetic activity (KP > 4), they are 1.24, 1.68 and 7.62 TECU, respectively. For further analysis, the accuracy of three models in precise point positioning (PPP) has been also evaluated. In PPP method, there is an improvement of about 1–16 mm compared to GIM and NeQuick models at coordinate components of control stations in high geomagnetic activity. The results of the analysis performed in this paper show that the FE model has a very high capability and accuracy in regional VTEC modeling in high and low geomagnetic conditions. The regional accuracy of this model is higher than GIM and NeQuick models and therefore can be considered as a new model for the ionosphere. [ABSTRACT FROM AUTHOR]

• Paper describes a methodology that was successfully applied for the development of a temporary road traffic steel barrier in compliance with T1/W1 level according to EN 1317; • A simplified theoretical analysis of 178 barrier, laboratory test of three types of barrier connectors (for two types of barrier), explicit FEM modeling of four chosen barrier, and a full-scale crash test for final barrier are presented; • The stiffness of barrier connector was established based by laboratory barrier test (the FEM model was validated based on laboratory tests); • The chosen final barrier alternative passed the crash test for T1/W1 (TB21) containment level, performed by certified laboratory [35] , which proves that the presented procedure could be used successfully for traffic barrier development. Over a million people die in road crashes and tens of millions result injured or disabled each year, globally. Hence, there is a constant concern for improving the safety of the roads to protect road users, and those at the most risk, the road workers. Construction, maintenance, and utility work are constantly needed to ensure safety and functionality of roads and highways. Temporary road traffic barriers are used to separate passing traffic from the workspace and protect the workspace from an errant vehicle intrusion. Steel barriers are light, and their major advantage is rapid installation. These barriers are not anchored to the ground, and their behavior relies on the base-pavement friction, mass inertia, and stiffness of the system. The paper describes a methodology that was successfully applied for the development of a temporary road traffic steel barrier in compliance with the European specification EN 1317. The study included a simplified theoretical analysis of 178 barriers, static laboratory tests of three types of barrier connectors, development of explicit finite element models (EFEMs) of four selected barrier designs, and a full-scale crash test of the final barrier design. It is shown that static laboratory tests of complex connector systems can help to improve the design process and reduce the cost. The analysis and use of EFEMs was enough so that just a single full-scale crash test was sufficient for certification of the barrier design for use in Europe. The final barrier is compliant with the EN 1317–2 requirements for T1/W1 (TB21) containment level, which was confirmed by a full-scale crash test. [ABSTRACT FROM AUTHOR]

The fatigue life of orthotropic steel bridge decks in road bridges depends on the load effects exerted by heavy lorries. The contact surface of tyres is one of the important variables. Measurements described in the literature demonstrate that the actual tyre contact surfaces of today's traffic representative for Europe are shorter and slightly wider than the contact surface defined for the load model in the European standard for fatigue loads in bridges — EN 1991-2. This paper derives a new, realistic tyre contact surface to be used with the tyre loads in EN 1991-2, in such a way that the load effects for fatigue are realistically captured and that the required safety level is met. • Fatigue of orthotropic bridge decks depends on the lorry tyre contact surface. • The contact surface in Eurocode's Fatigue Load Model 4 is too long and narrow. • The width of the traction axle (tyre-to-tyre distance) in the load model is too large. • The finite element method is used to calibrate the contact surface in the load model. • Realistic tyre contacts are therein compared to a square contact with uniform stress. [ABSTRACT FROM AUTHOR]

Abstract: Background: Vascular support structures are important devices for treating valve stenosis. Large population of patients are treated for valvular disease and the principal mode of treatment is the use of percutaneous valvuloplasty. Stent devices are proving to be an improved technology in minimal invasive cardiac surgery. This technology now accounts for 20% of treatments in Europe. This new technology provides highly effective results at minimal cost and short duration of hospitalization. Methods: This paper discusses the design and finite element analysis (FEA) of a percutaneous aortic valve stent. The stent design was modeled and subjected to FEA. The improved model design was carried out to meet the functional and surgical requirements. Analysis was done with different materials with loads ranging from 50 to 73 kgf/mm2. These forces were selected because these values are far greater than the normal human blood pressure which ranges from 10 to 16 kPa. It was also to understand the mechanical behavior of different stent materials under such high pressures. Results: A stent model was generated and its physical, mechanical, and behavioral properties were studied. Finite element analysis and simulation of the model help the designer to optimize the geometry suitable for performance during and after implantation. The design objective for the stent is to have long-term durability, low thrombogenicity, and resistance to migration and paravalvular leak. Conclusion: The analysis performed in this paper may aid in understanding the stent''s tolerable pressure ranges in comparison with the physiological pressures exerted by the heart and cardiac blood flow during abnormal cardiovascular conditions. It may also help in finding the material that will best suit the stent. [Copyright &y& Elsevier]

Abstract: During the ITER operation, various Test Breeding Modules (TBM) will be tested in the equatorial ports of the reactor. These TBMs are currently being developed in several research centres around in the world. The Helium-Cooled Pebble Bed (HCPB) blanket is one of two breeder blanket concepts developed in Europe. HCPB uses Beryllium pebbles act as a neutron multiplier and Li4SiO4 or Li2TiO3 pebbles act as breeder materials. The structural analysis of the breeding blanket is complex in terms of its geometry and loading conditions. Advanced computer codes are needed in order to determine the reliability of the various designs. In this context the mechanical characterization of pebble beds is important in order to simulate their behaviour. This paper illustrates three-axial experimental tests performed on Li2TiO3 pebble beds. In addition, preliminary results of the numerical simulations are shown. The numerical analyses were performed using an original model, based on the elastic–plastic behaviour of a single pebble, implemented in an FEM code. The paper highlights the importance of the confining pressure on the mechanical behaviour of pebble beds and the possibility of simulating them with homogeneous materials. [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]

• The impact of a pendulum hitting five obstacles with a similar mass is studied. • The studied system models the crash of a vehicle into various anti-terror barriers. • The combination of experiments and FEA highlights the properties the barrier needs. • A powerful mobile barrier should be deformable and use water to dissipate energy. • A ballast made of metals positioned in the lower part reduces the displacement. The most important recent terrorist attacks in Europe consist of vehicles rammed into crowds. The current response to this phenomenon is the adoption of concrete barriers, whose effectiveness is still not clear. The authors of this paper have already designed an innovative mobile anti-terror barrier which combines high performance and good look. This paper explains the most significant concepts which have been used for the design of this new barrier with the help of simple models. In detail, the impact of a pendulum hitting some obstacles with a similar total mass is investigated by means of experimental tests and finite element analysis. The purpose of this study is to identify the best solution which most efficiently stops the impacting object. The results show that a powerful mobile system should be extremely deformable and use water to dissipate energy. A ballast made of metals positioned in the lower part of the anti-terror system helps to reduce the total displacement of the barrier itself. [ABSTRACT FROM AUTHOR]

This paper presents the development of efficient design equations for high strength steel (HSS) welded I-section beam–columns under the framework of the Continuous Strength Method (CSM). The present work includes a collection of available experimental data on HSS S690 and S960 welded I-section beam–columns and a comprehensive numerical modelling programme considering a wider spectrum of parameters that influence the structural behaviour of the HSS welded I-section beam–columns. The developed FE models were first validated against test results collected from the literature, after which parametric studies were performed to generate further results to assess the accuracy of the codified design methods as used in Europe and the US, as well as to underpin new design proposals for HSS non-slender welded I-section beam–columns. It has been shown that the proposed CSM-based design approach is able to provide reliable design predictions with improved accuracy and reduced scatter over the existing design methods, and its reliability has been confirmed by means of statistical analyses. • Numerical models validated against test results for HSS beam–columns. • Validated numerical models used to perform parametric studies considering key parameters. • Current European and American design provisions assessed using the experimental and numerical data. • The Continuous Strength Method extended to cover the design of HSS beam–columns with welded I-sections. • Reliability of the CSM evaluated by means of statistical analyses according to EN 1990. [ABSTRACT FROM AUTHOR]

Abstract: Experimental re-entry demonstrators are currently being developed in Europe, with the objective of increasing the technology readiness level (TRL) of technologies applicable to future reusable launch vehicles. Among these are the Pre-X programme, currently funded by CNES, the French Space Agency, and which is about to enter into development phase B, and the IXV, within the future launcher preparatory programme (FLPP) funded by ESA. One of the major technologies necessary for such vehicles is the thermal protection system (TPS), and in particular the ceramic matrix composites (CMC) based windward TPS. In support of this goal, technology maturation activities named “generic shingle” were initiated beginning of 2003 by SPS, under a CNES contract, with the objective of performing a test campaign of a complete shingle of generic design, in preparation of the development of a re-entry experimental vehicle decided in Europe. The activities performed to date include: the design, manufacturing of two C/SiC panels, finite element model (FEM) calculation of the design, testing of technological samples extracted from a dedicated panel, mechanical pressure testing of a panel, and a complete study of the attachment system. Additional testing is currently under preparation on the panel equipped with its insulation, seal, attachment device, and representative portion of cold structure, to further assess its behaviour in environments relevant to its application The paper will present the activities that will have been performed in 2006 on the prediction and preparation of these modal characterization, dynamic, acoustic as well as thermal and thermo-mechanical tests. Results of these tests will be presented and the lessons learned will be discussed. [Copyright &y& Elsevier]