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Comerç i ciutat
No full textEl sector del comerç exerceix un paper fonamental en l'economia catalana, essent un eix dinamitzador de ciutats com Barcelona. L’any 2023, el creixement del PIB de Barcelona ha estat superior al de Catalunya (2,6%) i d’Espanya (2,5%), fet que s’explica per un predomini del sector serveis en l’economia de la ciutat respecte a la dels altres territoris, i especialment gràcies a aquelles activitats amb més volum de valor afegit brut (VAB) com són el comerç, el transport i la hostaleria, que representen un 23,6%.
A partir de l’anàlisi de diferents fonts d’informació i estudis sòcio-econòmics publicats, volem obtenir una radiografia del moment present del comerç de Barcelona, de les seves fortaleses i debilitats, dels seus principals reptes i oportunitats, per tal d’identificar les palanques que contribuiran al desenvolupament estratègic del sector a mig termini, preservant la seva vertebració social en el territori
Critical review of applicable standards and gaps identification in FRP offshore structures (T4.3.1)
No full textThe conclusions of an extensive review of the regulations and standards related to the use of conventional (steel and concrete) and unconventional materials (FRP materials and others) on marine structures will be included in this report, as well as the gaps that need to be filled in in the future by regulatory bodies to enable the rolling out of OWTP platforms in FRP materials.
A two-tier strategy will be performed with the fundamental objective to carry out the critical review. Firstly, it will be carried out an analysis of the potential standards for the application of FRP materials in the design of offshore structures. Secondly, it will be identified the existing gaps for the application of FRP materials in the design of the W2Power and the TIDETEC’s turntable tidal turbine developed in FIBREGY.
The findings of this report will be used as the background of the deliverable 4.7 focused on the development of project design guidelines and recommendations for using FRP in large OWTPs
Construction of the turbine housing demonstrator
Get PDFThis deliverable will include the Tidetec’s turnable turbine housing large demonstrator and
a related detailed report in which the design process of the respective tooling (mandrels) and filament winding process simulation and manufacturing will be describe
Multi-scale procedure for the mechanical analysis of composite laminate structures considering mixed boundary conditions
Get PDFThis paper presents a multi-scale procedure for the study of flat composite structures with discontinuities. In this procedure, the structure is solved using shell elements while the laminate performance and the structural discontinuities (e.g. connections or change in the laminate thickness) are analysed with a subscale model made with solid 3D elements. The kinematics of both models are coupled following the Kirchhoff–Love theory. This coupling is used during the homogenization procedure where the characteristic behaviour of the different micro-models is obtained. Periodical boundary conditions are used for the laminates whereas a combination between periodical and linear boundary conditions are used for the discontinuities. The proposed procedure allows to reproduce accurately the structure elastic behaviour, as well as the stress and strain states in regions with discontinuities, which until now could only be accurately simulated by means of expensive numerical models using volumetric solid elements
Time-resolved subcycle and intercycle interference influenced momentum shift in nonadiabatic tunnelling ionization
No full textMomentum shift is an important sign of nonadiabatic tunnelling ionization process, to investigate the mechanism of momentum shift, we use the strong-field approximation theory to track the formation of ionization momentum spectra of hydrogen atom under the action of different laser pulses in time domain. By observing the ionization momentum spectra of different structures with time, we find that the momentum shift is formed by the continuous interference and evolution of ionization signals over time. Meanwhile, we further analyze how subcycle and intercycle interference influencing the formation of momentum shift. Before the duration is long enough that intercycle interference emerges, momentum shift grows smoothly. This finding reveals the different intrinsic mechanisms for the formation of momentum shift in many-cycle and few-cycle laser pulses. This work lays foundation for deeper understanding of nonadiabatic tunnelling process and makes the regulation of momentum shift possible
Numerical Investigation of the Installation of Suction Caisson in Sand Using Material Point Method
Get PDFSuction caisson has gained interest in recent years as an alternative foundation for offshore wind turbines due to its cost-effectiveness and easy installation compared to conventional foundations such as monopile. After initial penetration due to its self-weight, suction is applied until the caisson reaches the desired depth. Applying suction provides additional driving force due to the pressure difference between inside and outside the caisson and induces seepage that degrades friction and tip resistance, which further facilitates the installation. The seepage plays a vital role in installing suction caisson in sand; however, it might change the soil state which affects the ultimate bearing capacity of the caisson. Several research works have been conducted to study the suction caisson installation in sand. However, the complexities of the problem including large deformation, solid-fluid and soil-structure interaction, inhibited these studies from fully understanding the installation mechanism. This paper proposes a large deformation modeling framework by using the material point method (MPM). MPM is a hybrid Lagrangian-Eulerian particle-based method that uses material points over a fixed computational mesh where governing equations are solved. During the convection of the particles, the background mesh is kept fixed, making it suitable for large deformation problems. The model considers soil-structure interaction by adopting a Coulomb contact algorithm between the caisson and surrounding soil. In this paper, the stability of the contact algorithm is ensured by correcting material point velocities in the vicinity of the caisson interface using a limiting velocity based on the element size and time step. The framework is validated by comparing a simulation of caisson installation under constant velocity with results published in the literature. Our proposed framework’s results agree with previous published results, demonstrating that the simplified stabilization procedure does not affect the simulation results. This is a promising result that will enable the incorporation of fully coupled analysis to better understand the effects of induced seepage on the installation mechanism of suction caissons
Multiscale modeling of hydrogen transport in steels and its resulting embrittlement effect
Get PDFA multiscale modeling approach is adopted in this study to understand the hydrogen embrittlement (HE) mechanisms and to predict failure of engineering components under the influence of hydrogen environment. Molecular dynamics simulations of the bodycentered cubic (BCC) iron are conducted to examine the theories of hydrogen enhanced localized plasticity (HELP) and hydrogen enhanced decohesion (HEDE). It is shown that hydrogen aggregation at the crack tip and along grain boundary (GB) reduces the surface energy for creating new crack surfaces, leading to changes in fracture modes caused by preemptive crack propagation. At the continuum level, a numerical framework is developed, which incorporates hydrogen transport in steels and the resulting HELP and HEDE mechanisms into a finite element phase field model to predict crack initiation and propagation in engineering components. As an example, a compact tension (CT) specimen made of a pipeline steel is analyzed. The numerical model captures the phenomenon of hydrogen aggregation occurring proximal to the crack tip driven by the high gradient of hydrostatic stress and large plastic deformation in this region. The resultant hydrogen concentration elicits an interplay of HELP and HEDE effects and reduces the specimen’s load carrying capacity. With properly chosen model parameters, the numerical model has the potential of serving as tool for predicting crack propagation and ductile to brittle transition due to the presence of hydrogen
The Picard-Newton iteration for the Boussinesq equations
No full textWe consider the Picard-Newton and Anderson accelerated Picard-Newton solvers applied to the Boussinesq equations, nonlinear Helmholtz equations and Liouville equation, for the purpose of accelerating convergence and improving robustness with respect to problem parameters. In all cases, we show the proposed solvers improve efficiency over the commonly used solvers and are able to find solutions for a much larger set of problem parameters
Hybrid structure health monitoring technique for enhancing modal parameter identification accuracy
Get PDFSHM relies on the possibility of estimating structural modal parameters, such as mode shapes, natural frequencies, and damping, from the structure’s measured data. Nevertheless, modal parameter estimation still faces accuracy problems. The identification of bridge and/or vehicle system parameters and vibration characteristics have been studied both numerically and experimentally. The knowledge of bridge vibration characteristics and vehicle system parameters is crucial to the maintenance of bridges. The issue is that the techniques used to identify bridge and vehicle system parameters usually work very well with numerical simulation but present accuracy issues with experimental data due to environmental noise. Traditionally, measured data were obtained by instrumenting bridges with connected sensor systems, which had issues such as high cost, maintenance problems, safety concerns, and traffic disruption. More recently, indirect SHM (iSHM) methods, such as drive-by using passing instrumented vehicles, have been researched[1,2]. However, these methods still struggle with the accuracy of modal parameter identification, particularly for higher vibration modes sensitive to localized bridge damage, limiting the widespread adoption of iSHM methodologies[1,3]. A combination of indirect and direct monitoring methods is proposed to address these limitations. This approach aims to improve modal parameter identification, including higher vibration modes, for localized damage detection and structural assessment. The proposed method uses GPS-time synchronized sensors for simultaneous measurement of vehicle and bridge vibration data and is verified through numerical simulation assuming multiple runs over the same bridge. The study highlights the potential of this hybrid SHM technique to significantly improve the accuracy of indirect structural health monitoring, providing more reliable and precise modal parameter estimates, especially for higher vibration modes, allowing for the identification of localized bridge damage
Development of a design methodology for slender carbon-reinforced concrete columns in axial compression based on EC3
Get PDFAdvancements in concrete construction, such as carbon-reinforced and ultra-high performance concretes, enable the creation of slender, high-capacity structures, enhancing resource efficiency and reducing CO2 emissions. Despite the clear advantages of such innovative material composites, challenging load-bearing and deformation behavior emerges in slender carbon-reinforced concrete components, indicating potential stability issues. To address this concern, current research is dedicated to experimental and analytical investigations of the structural behavior and failure of slender components in compression made of carbon reinforced concrete, aiming to enhance our understanding of stability-related aspects