Optimization-based comparison of different approaches for the automatized calculation of residual stresses and fiber orientations in arteries

Residual stresses and fiber orientations in arterial walls can be approximated by means of the simulation of growth and remodeling processes. In order to enable a comparison of different approaches of combined growth and remodeling in one framework, a method based on the optimization of model parameters is developed. The minimization of a mechano-biologically motivated objective function permits to evaluate the approaches with respect to their ability of effectively reducing stress peaks and stress inhomogeneities in the arterial wall. This examination is performed for a simplified, one-layered, rotationally symmetric arterial segment in order to enable the analysis of the fundamental mechanisms included in the individual model variants. Once the most probable growth mechanism is identified, multi-layered segments can be analyzed in more detail

Fine tuning of MLCT states in new mononuclear complexes of ruthenium(II) containing tris(1-pyrazolyl)methane, 2,2′-bipyridine and aromatic nitrogen heterocycles

The syntheses of new mononuclear ruthenium(II) complexes of the type: [Ru(bpy)(L)(tpm)](PF6)2 {tpm = tris(1-pyrazolyl)-methane; bpy = 2,2′-bipyridine; L = pz (pyrazine; 1), 4,4′-bpy (4,4′-bipyridine; 2), and bpe [trans-1,2-bis(4-pyridyl)ethylene; 3]} are described, together with their spectroscopic, electrochemical, and photophysical properties. A complete assignment of the NMR resonances of the three species could be made in CD3CN by bidimensional techniques. A fine tuning of the energies of MLCT (metal-to-ligand charge transfer) states in these complexes is disclosed when comparing, in CH3CN, the values of their maximum absorption wave-lengths for the most intense visible bands (λ max) and their redox potentials for the RuIII/Ru II couples; this effect, relevant to the design of efficient photocatalysts, can be attributed to a decreasing order of dπ(Ru) →*(2,2′-bpy) backbonding when decreasing the distance between both N atoms in the aromatic nitrogen heterocycle L that acts in a monodentate manner. Only the species with L = bpe emits at room temperature, pointing to the conclusion that MLCT excited states in this series become higher in energy than dd excited states when the value of λmax is lower than 400 nm. These species are also useful building blocks for new dinuclear mixed-valent complexes. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.Fil: Katz, Néstor Eduardo. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Romero, Isabel. Universidad de Girona; EspañaFil: Llobet, Antoni. Universidad de Girona; EspañaFil: Parella, Teodor. Universitat Autònoma de Barcelona; EspañaFil: Benet Buchholz, Jordi. Bayer Industry Services; Alemani

3D Data Processing Toward Maintenance and Conservation. The Integrated Digital Documentation of Casa de Vidro

During the last decade, 3D integrated surveys and BIM modelling procedures have greatly improved the overall knowledge on some Brazilian Modernist buildings. In this framework, the Casa de Vidro 3D survey carried out by DIAPReM centre at Ferrara University, beside the important outputs, analysis and researches achieved from the point cloud database processing, was also useful to test several awareness increasing activities in cooperation with local stakeholders. The first digital documentation test of the Casa de Vidro allowed verifying the feasibility of a full survey on the building towards the restoration and possible placement of new architectures into the garden as an archive-museum of the Lina Bo and P.M. Bardi Foundation. Later, full 3D integrated survey and diagnostic analysis were carried out to achieve the total digital documentation of the house sponsored by the Keeping it Modern initiative of Getty Foundation (Los Angeles). Following its characteristics, the survey had to take into consideration the different architectural features, up to the relationship of architecture and nature. These 3D documentation activities and the point cloud processing allowed several analysis in a multidisciplinary framework

Modeling and experimental investigations of the stress-softening behavior of soft collagenous tissues

This paper deals with the formulation of a micro-mechanically based dam-age model for soft collagenous tissues. The model is motivated by (i) a sliding filament model proposed in the literature [1] and (ii) by experimental observations from electron microscopy (EM) images of human abdominal aorta specimens, see [2]. Specifically, we derive a continuum damage model that takes into account statistically distributed pro- teoglycan (PG) bridges. The damage model is embedded into the constitutive framework proposed by Balzani et al. [3] and adjusted to cyclic uniaxial tension tests of a hu- man carotid artery. Furthermore, the resulting damage distribution of the model after a circumferential overstretch of a simplified arterial section is analyzed in a finite element calculation

Analyse des pratiques professionnelles d'accompagnement des chomeurs

Chapitre rapport de recherche DARESNational audienceDans ce chapitre du rapport remis à la DARES en 2008 sur "l'accompagnement des chômeurs dans et vers l'emploi", sont présentés les résultats du recueil de données portant sur l'analyse des pratiques professionnels des conseillers en emploi

An extended Hamilton principle as unifying theory for coupled problems and dissipative microstructure evolution

An established strategy for material modeling is provided by energy-based principles such that evolution equations in terms of ordinary differential equations can be derived. However, there exist a variety of material models that also need to take into account non-local effects to capture microstructure evolution. In this case, the evolution of microstructure is described by a partial differential equation. In this contribution, we present how Hamilton’s principle provides a physically sound strategy for the derivation of transient field equations for all state variables. Therefore, we begin with a demonstration how Hamilton’s principle generalizes the principle of stationary action for rigid bodies. Furthermore, we show that the basic idea behind Hamilton’s principle is not restricted to isothermal mechanical processes. In contrast, we propose an extended Hamilton principle which is applicable to coupled problems and dissipative microstructure evolution. As example, we demonstrate how the field equations for all state variables for thermo-mechanically coupled problems, i.e., displacements, temperature, and internal variables, result from the stationarity of the extended Hamilton functional. The relation to other principles, as the principle of virtual work and Onsager’s principle, is given. Finally, exemplary material models demonstrate how to use the extended Hamilton principle for thermo-mechanically coupled elastic, gradient-enhanced, rate-dependent, and rate-independent materials. © 2021, The Author(s)

An extended Hamilton functional for the thermodynamic topology optimization of hyperelastic structures

We present our work on a new variational approach for thermodynamic topology optimization of hyperelastic structures: building upon our previous works, we follow a thermodynamic approach for deriving a field equation that describes the evolution of the density. The problem of topology optimization is consequently solved without the need of expensive optimization routines. Furthermore, our new formulation can also be applied to hyperelastic structures which show a remarkable difference to structures optimized for small deformations. Important aspects like tension/compression asymmetry and buckling are inherently included in the topology optimization approach due to the large deformation formulation

MODELING OF ANISOTROPIC GROWTH AND RESIDUAL STRESSES IN ARTERIAL WALLS

Based on the multiplicative decomposition of the deformation gradient, a local formulation for anisotropic growth in soft biological tissues is formulated by connecting the growth tensor to the main anisotropy directions. In combination with an anisotropic driving force, the model enables an effective stress reduction due to growth-induced residual stresses. A method for the imitation of opening angle experiments in numerically simulated arterial segments, visualizing the deformations related to residual stresses, is presented and illustrated in a numerical example

Blockchain and sustainability disclosure: reliable information on renewable energies

Purpose: The energy transition and companies\u27 commitment to sustainability look at new technologies support. We aim to understand how blockchain technology improves the traceability of renewable energy origin and provides reliable information for companies\u27 sustainable disclosure regarding renewable energy use and greenhouse gas emissions. Design: We conducted a literature review regarding the support of blockchain technology on sustainability disclosure, focusing on reliability through the traceability of renewable energy certificates. We use a qualitative methodology, analysing two case studies. Findings: The blockchain technology capabilities are recognised by the sector operators, especially for their support in information management and reliability. Blockchain capabilities are identified in renewable energy certification traceability and GHG emissions evaluation, mainly within Scope 3, as reliable information sources for sustainability disclosure. Emerges that the improvement through other devices and regulations might foster the system development. Moreover, blockchain application in the energy sector is a primary phase that needs more time to develop its potential. Originality/value: Although there is abundant literature on companies\u27 environmental information, very few studies support the transparency and reliability of renewable energy origin information, considering the technological support of blockchain to guarantee the renewable nature of the energy consumed. First, insights are provided within the idea that blockchain might foster and guide sustainability disclosure through reliable information. Research implications: The analysis invites interaction between academics, energy sector operators and legislators. It provides reliable information to ensure integration with financial information following an integrating thinking logic

Residual stresses resulting from growth and remodeling in arterial walls

A model for multiplicative anisotropic growth in soft biological tissues, which relates the growth tensor to the fibrous tissue structure, is combined with a fiber remode- ling framework. Both adaptation mechanisms are supposed to be governed by the intensity and the directions of the tensile principal stresses. Numerical examples on idealized arterial segments, illustrating stress and fiber angle distributions as well as resulting residual stresses in cases with and without fiber remodeling, are presented. It turns out that all processes including growth and remodeling are necessary to obtain qualitatively realistic distributions of fiber orientations, residual stresses, and stresses under loading