Advanced FE models of stiffened cleat angle connections

Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.In this paper, the development of reliable 3D FE models of stiffened angle connections is dealt with. These advanced models will permit to obtain the assessment of the 3D deformational response of some future tests. Abaqus® finite element code was used to carry the 3D finite element analyses out. Symmetry was considered for these numerical analyses so a quarter of the geometry was modelled. The results obtained are compared with those from the analysis of the analogous specimens but without the top angle stiffener, showing an important increase in the initial connection stiffness. At the same time, the stress increment in the column panel zone due to the presence of the angle stiffener has been discussed

Artificial neural network prediction of the initial stiffness of semi-rigid beam-to-column connections

[Abstract]: Joints are significant components in the design and construction of steel structures. The characteristic parameters of the connections must be reproduced in a reliable way to represent the actual behaviour of a structure. Accordingly, the study of semi-rigid joints is essential to better understand this issue. Among the different types of semi-rigid joints, angle connections stand out as a suitable solution in many cases. This paper presents a methodology using artificial neural networks for predicting the initial rotational stiffness of major axis symmetrical angle connections according to the Eurocode description. A consistent stiffness database was developed from the existing data in the Steel Connection Data Bank. Then, the database was cleansed to provide with a robust training set. Different network architectures were analysed until a topology that showed a good performance and generalisation features was obtained. The network was successfully checked with some saved tests from the database and with off-database tests; the network could be reliably used within the range of the training input parameters.Ministerio de Ciencia e Innovación; PID2020-113895GBC3

Towards an optimal adaptation of exposure to NOAA assessment methodology in Multi-Source Industrial Scenarios (MSIS): the challenges and the decision-making process

It is expected a progressive increase of the industrial processes that manufacture of intermediate (iNEPs) and end products incorporating ENMs (eNEPs) to bring about improved properties. Therefore, the assessment of occupational exposure to airborne NOAA will migrate, from the simple and well-controlled exposure scenarios in research laboratories and ENMs production plants using innovative production technologies, to much more complex exposure scenarios located around processes of manufacture of eNEPs that, in many cases, will be modified conventional production processes. Here will be discussed some of the typical challenging situations in the process of risk assessment of inhalation exposure to NOAA in Multi-Source Industrial Scenarios (MSIS), from the basis of the lessons learned when confronted to those scenarios in the frame of some European and Spanish research projects.This paper exploits the results of the research developed by projects SCAFFOLD and EHS Advance. Project SCAFFOLD received funding from the European Union's FP7 research and innovation programme, under grant agreement No. 280535. Project EHS Advance received funding from the Basque Government research programme (Etortek). The authors would also like to express their grateful to companies BOSTLAN (Bizkaia, Spain) and TECNAN (Navarra, Spain) for the support provided to carry out the exposure measurements in their respective facilities

Note on "An efficient approach for solving the lot-sizing problem with time-varying storage capacities"

In a recent paper Gutiérrez et al. (2008) show that the lot-sizing problem with inventory bounds can be solved in O(T log T) time. In this note we show that their algorithm does not lead to an optimal solution in general

Experimental evidence of a cluster-glass transition on the colossal magnetoresistance manganite La0.7Pb0.3(Mn0.9Fe0.1)O3

4 págs.; 3 figs. ; PACS numberssd: 75.40.2s, 75.47.2m, 61.12.Ex, 61.46.1wNeutron small angle scattering on a colossal magnetoresistance material shows clear signatures of a rise in characteristic length of paramagnetic fluctuations as the maximum of dc susceptibility is approached from high temperatures. The phenomenon is accompanied by a rise in intensity of a broad peak that appears at wave vectors of ≈ 0.025-1, and this is interpreted as a fingerprint of the onset of ferromagnetic ordering due to intercluster magnetic interactions. © 2005 The American Physical Society.Peer Reviewe

Acute toxicity, bioaccumulation and effects of dietary 1 transfer of silver from brine 2 shrimps exposed to PVP/PEI-coated silver nanoparticles to zebrafish

The extensive use and release to the aquatic environment of silver nanoparticles (NPs) could lead to their incorporation into the food web. Brine shrimp larvae of 24 h showed low sensitivity to the exposure to PVP/PEI-coated Ag NPs (5 nm), with EC50 values at 24 h of 19.63 mg Ag L-1, but they significantly accumulated silver after 24 h of exposure to 100 μg L-1 of Ag NPs. Thus, to assess bioaccumulation and effects of silver transferred by the diet in zebrafish, brine shrimp larvae were exposed to 100 ng L-1 of Ag NPs as an environmentally relevant concentration or to 100 μg L-1 as a potentially effective concentration and used to feed zebrafish for 21 days. Autometallography revealed a dose- and time-dependent metal accumulation in the intestine and in the liver of zebrafish. Three-day feeding with brine shrimps exposed to 100 ng L-1 of Ag NPs was enough to impair fish health as reflected by the significant reduction of lysosomal membrane stability and the presence of vacuolization and necrosis in the liver. However, dietary exposure to 100 μg L-1 of Ag NPs for 3 days did not significantly alter gene transcription levels, neither in the liver nor in the intestine. After 21 days, biological processes such as lipid transport and localization, cellular response to chemical stimulus and response to xenobiotic stimulus were significantly altered in the liver. Overall, these results indicate an effective dietary transfer of silver and point out to liver as the main target organ for Ag NP toxicity in zebrafish after dietary exposure.MINECO (NanoSilverOmicsproject- MAT2012-39372) Basque Government (consolidated research groups IT810-13 and IT620-13; Saiotek S-PE13UN142) University of the Basque Country (UFIs 11/37 and 11/52)

WSPH and ISPH Calculations of a Counter-Rotating Vortex Dipole

Viscosity and vorticity are magnitudes playing an important role in many engineering physical phenomena such as: boundary layer separation, transition flows, shear flows, etc., demonstrating the importance of the vortical viscous flows commonly used among the SPH community. The simulation presented here, describes the physics of a pair of counter-rotating vortices in which the strain field felt by each vortex is due to the other one. Different from the evolution of a single isolated vortex, in this case each vortex is subjected to an external stationary strain field generated by the other, making the streamlines deform elliptically. To avoid the boundary influence, a large computational domain has been used ensuring insignificant effect of the boundary conditions on the solution. The performance of the most commonly used viscous models in simulating laminar flows, Takeda’s (TVT), Morris’ (MVT) and Monaghan-Cleary’s (MCGVT) has been discussed comparing their results. These viscous models have been used under two different compressibility hypotheses. Two cases have been numerically analyzed in this presentation. In the first case, a 2D system of two counter-rotating Lamb O seen vortices is considered. At first, the system goes through a rapid relaxation process in which both vortices equilibrate each other. This quasi-steady state is obtained after the relaxation phase is advected at a constant speed and slowly evolves owing to viscous diffusion. The results of the different Lamb-O seen numerical solutions have been validated with good agreement by comparison with the numerical results of a finite element code (ADFC) solution. A second case, somewhat more complex than the previous one, is a 3D Batchelor vortex dipole obtained by adding an axial flow to the system of the first case. The Batchelor vortex model considered here is a classical option normally used to model the structure of trailing vortices in the far-wake of an aircraft