Relatedness, Coherence, and Coherence Dynamics Empirical Evidence from Italian Manufacturing

This paper investigates the determinants of coherence and coherence change using a sample of Italian leading firms in the period 1993-1996. Following a methodology developed by Teece et al (1994), the observed diversification patterns of our sample firms provide the information required to construct an index of relatedness between pair of sectors, which is in turn used to obtain a measure of firm’s coherence. The econometric analysis highlights that relatedness is higher when sectors share similar technological and marketing characteristics, and when they are positioned at different stages of the productive chain. Analogously, coherence is higher for firms active in industries characterised by similar R&D intensities and exploiting vertical integration links. Firms which enter the group of top 5 leaders are more coherent than the average. From a dynamic perspective, we find that coherence increases for firms with main activities in sectors which are expected to be more affected from EU integration. Finally, the results show that a deepening of vertical integration strategies is good for coherence change, while an increase of diversification brings a reduction in coherence.relatedness, coherence, diversification

Development of computational efficient shell formulation for analysis of multilayered structures subjected to mechanical, thermal, and electrical loadings

The aim of this work is the development of robust finite shell model suitable for numerical applications in solid mechanics with a remarkable reduction in computational cost. Two-dimensional (2D) structural models, commonly known as plates/shells, are for instance used in many applications to analyze the structural behavior of thin and slender bodies such as panels, domes, pressure vessels, and wing stiffened panels amongst others. These models reduce the three-dimensional 3D problem into a two-dimensional 2D problem, where variables depend on the in-plane axis coordinates. Two-dimensional elements are simpler and computationally more efficient than 3D (solid) models. This feature makes plate/shell theories still very attractive for the static, dynamic response, free vibration, thermo-mechanical and electro-mechanical analysis, despite the approximations which they introduce in the simulation. Nevertheless, analytical solutions for three-dimensional elastic bodies are generally available only for a few particular cases which represent rather coarse simplifications of reality. In most of the practical problems, the solution demands applications of approximated computational methods. The Finite Element Method (FEM) has a predominant role among the computational techniques implemented for the analysis of layered structures. The majority of FEM theories available in the literature are formulated by axiomatic-type theories. In this thesis, attention is focused on weak-form solutions of refined plate/shell theories. In particular, higher-order plate/shell models are developed within the framework of the Unified Formulation by Carrera, according to which the three-dimensional displacement field can be expressed as an arbitrary expansion of the generalized displacements. A robust finite shell element for the analysis of plate and shell structures subjected to mechanical, thermal, and/or electrical loadings is developed. A wide range of problems are considered, including static analysis, free vibration analysis, different boundary conditions and different laminations schemes, distributed pressure loads, localized pressure loads or concentrated loads are taken into account. The high computational costs represent the drawback of refined plate/shell theories or three-dimensional analyses. In recent years considerable improvements have been obtained towards the implementation of innovative solutions for improving the analysis efficiency for a global/local scenario. In this manner, the limited computational resources can be distributed in an optimal manner to study in detail only those parts of the structure that require an accurate analysis. In the second part of the thesis two different methodology are presented to improve the analysis efficiency, and at the same time keeping the finite higher-order plate/shell element accuracy. The two approaches can be collocated in the simultaneous multi-model methodologies. The first is the Mixed ESL/LW variable kinematic method, where the primary variables are described along the shell thickness selecting some plies with an ESL description and others with a LW behaviour by using the Legendre polynomials for both the assembling approaches. The second approach is a new simultaneous multi-model, here presented as Node-Dependent Variable Kinematic method. The shell element with node-dependent capabilities enables one to vary the kinematic assumptions within the same finite element. The expansion order ( along the shell thickness ) of the shell element is, in fact, a property of the FE node in the present approach. Different kinematics can be coupled without the use of any mathematical artifice. The theories developed in this thesis are validated by using some selected results from the literature. The analyses suggest that Unified Formulation furnishes a reliable method to implement refined theories capable of providing almost three-dimensional elasticity solution, and that the two simultaneous multi-theories methods are extremely powerful and versatile when applied to composite or sandwich structures subjected to various mutlifield loadings

HOMOGENISED PROPERTIES OF LATTICE METAL COMPOSITE CELL

In this paper, the mechanical analysis of an advanced Body Centred Cubic (BCC) lattice cell has been performed through a homogenisation procedure to obtain an equivalent set of mechanical properties. The mechanical analyses have been carried out with the use of ANSYS software and an original ANSYS Parametric Design Language (APDL) subroutine has been developed for the introduction of the double periodic boundary conditions. The Finite Element Method (FEM) is used for the mechanical model, and 3D elements with reduced integration has been employed to guarantee an accurate description of the lattice geometry. Different BCC cell configurations have been considered: standard metal BCC cell, metal BCC cell with waved struts, standard metal composite BCC cell. Depending on the configuration, the homogenised materials showed isotropic or orthotropic properties. For the evaluation of all the engineering constants, uniaxial traction test and in-plane shear test have been simulated along different loading directions. A parametric study has been conducted varying the struts diameter, the struts waviness and the thickness ratio of the composite struts. Finally, the homogenised materials have been tested through the mechanical analysis of sandwich panels with lattice core; a comparison between sandwich panels with homogenised core and sandwich panels with exact lattice cells has been carried out. The parametric study can be useful for the tailoring and optimisation analysis of an advanced component

Traumatic Injury and Identity: Incorporating Traumatic Episodes into the Life Story

With an increasing number of traumatic injury survivors, a better understanding of post-trauma meaning-making processes is needed, including improvement in our understanding of post-trauma narrative reconstruction. This project aimed to identify emergent themes within the life story narratives of spinal cord injured veterans and to both generate and test hypotheses regarding how emergent themes related to an indicator of post-trauma wellness. Seven themes were revealed within two specific sections of the life story interview. Findings revealed that individuals who author their life narratives in such a way as to demonstrate altruism and generativity showed significantly higher wellness. Further, narratives with a greater mention of faith, as well as those with imagined futures reflecting a more affirming tone, tended to be authored by individuals with higher levels of wellness. Results help to further our understanding of how those who have been traumatically injured construct their post-injury identity and inform our understanding of resiliency in a traumatic injury population

Long term effects of mesoglycan on brachial arterial stiffness and MMP-9/TIMP-1 system in patients with metabolic syndrome

Objectives: The aim of this study was to evaluate the chronic effects of mesoglycan on the vascular remodeling in patients with metabolic syndrome (Mets). Background: MetS is defined by a clustering of vascular risk factors that require both pharmacologic and non-pharmacologic interventions, including body weight reductions and physical activity. The correction of vascular remodeling associated with MetS has lately received increasing interest. Methods: Thirty consecutive ambulatory patients affected by MetS were 2:1 randomized in a doubleblind fashion to receive mesoglycan or placebo, respectively. At the beginning and after 90 days of oral treatment we appraised the effects of mesoglycan (50 mg per os bid) or placebo on vascular remodeling, as assessed by the measurement of arterial wall elastic properties. Moreover, the matrix metalloproteinase’s (MMPs) type 9 and tissue inhibitor of metalloproteinase (TIMP) type 1 were analyzed by enzyme-linked immune sorbent assay (ELISA) and gelatin substrate zymography at the beginning of the study and after 90 days of treatment. Results: After 90 days of treatment, a marked improvement of arterial distensibility and compliance was detected in Mesoglycan group, with associated significant reduction of arterial stiffness, and a significant reduction of serum levels of MMP-9 and TIMP-1 and significant reduction of enzyme activity of MMPs. Conclusions: This small, preliminary study shows that mesoglycan exerts relevant effects on vascular remodeling after three-month treatment, in patients affected by metabolic syndrome

Thermo-Mechanical Structural Optimisation of a Chemical Propulsion Satellite Thruster Using Lattice Structures

Small satellite space thrusters are designed to provide force for short time periods. • New generation of thrusters will be made with High Entropy Alloy (HEA) materials. • Predicting damage initiation for this kind of metallic structure subjected to thermal shock is of fundamental importance. • The preliminary thermal-stress analysis is mandatory in order to understand the complex failure mechanism of the space thruster. • An optimisation analysis of the material distribution along the combustion chamber thickness can lead to an improvement of the thermal-stress response