Search results for " Connection"
showing 10 items of 138 documents
Analytical prediction of the shear connection capacity in composite steel–concrete trussed beams
2016
Steel–concrete trussed composite beams are a particular types of composite girders constituted by a steel truss embedded in a concrete core. The truss is typically composed by a steel plate or a precast concrete slab working as bottom chord while coupled rebars are generally used to form the upper chord. Moreover, a system of ribbed or smooth steel rebars welded to the plate and forming the diagonals of the truss, works as web reinforcement. In the present study, the attention is focused on the evaluation of the shear resistance of the connection between bottom steel plate (the bottom chord) and concrete core through the diagonal bars of the truss developing a mechanical model able to accou…
LRPH device optimization for axial and shear stresses
2020
The paper concerns an in-depth study of a special connection for steel structures and the formulation of the related optimal design problem. The connection is called Limited Resistance Rigid Perfectly Plastic Hinge (LRPH) and it represents an innovative device devoted to join steel beam elements of frame structures. The device consists in a sequence of steel cross sections constituted by two parallel flanges with suitably different thickness connected by as many webs with constant and equal thickness. The fundamental innovation of the device is the possibility of designing special connections with elastic stiffness and limit strength independent of each other. Such a special characteristic …
Topological electronic structure and Weyl points in nonsymmorphic hexagonal materials
2020
Using topological band theory analysis we show that the nonsymmorphic symmetry operations in hexagonal lattices enforce Weyl points at the screw-invariant high-symmetry lines of the band structure. The corepresentation theory and connectivity group theory show that Weyl points are generated by band crossings in accordion-like and hourglass-like dispersion relations. These Weyl points are stable against weak perturbations and are protected by the screw rotation symmetry. Based on first-principles calculations we found a complete agreement between the topological predicted energy dispersion relations and real hexagonal materials. Topological charge (chirality) and Berry curvature calculations…
The Riemannian manifold of all Riemannian metrics
1991
In this paper we study the geometry of (M, G) by using the ideas developed in [Michor, 1980]. With that differentiable structure on M it is possible to use variational principles and so we start in section 2 by computing geodesics as the curves in M minimizing the energy functional. From the geodesic equation, the covariant derivative of the Levi-Civita connection can be obtained, and that provides a direct method for computing the curvature of the manifold. Christoffel symbol and curvature turn out to be pointwise in M and so, although the mappings involved in the definition of the Ricci tensor and the scalar curvature have no trace, in our case we can define the concepts of ”Ricci like cu…
Homogeneous Weyl connections of non-positive curvature
2015
We study homogenous Weyl connections with non-positive sectional curvatures. The Cartesian product $\mathbb S^1 \times M$ carries canonical families of Weyl connections with such a property, for any Riemmanian manifold $M$. We prove that if a homogenous Weyl connection on a manifold, modeled on a unimodular Lie group, is non-positive in a stronger sense (streched non-positive), then it must be locally of the product type.
Finite-temperature geometric properties of the Kitaev honeycomb model
2018
We study finite temperature topological phase transitions of the Kitaev's spin honeycomb model in the vortex-free sector with the use of the recently introduced mean Uhlmann curvature. We employ an appropriate Fermionisation procedure to study the system as a two-band p-wave superconductor described by a BdG Hamiltonian. This allows to study relevant quantities such as Berry and mean Uhlmann curvatures in a simple setting. More specifically, we consider the spin honeycomb in the presence of an external magnetic field breaking time reversal symmetry. The introduction of such an external perturbation opens a gap in the phase of the system characterised by non-Abelian statistics, and makes the…
Development of a module of stacks of air-breathing microbial fuel cells to light-up a strip of LEDs
2018
Abstract This work focuses on scaling-up of the microbial fuel cells technology according to the principle of miniaturization and multiplication. Seven stacks of 16 mini-MFCs (electrodic area of 0.866 cm2) were built up leading to a big module of 112 MFCs. The electrical connection among the MFCs in the stacks and among the stacks into the modules was optimized in order to implement this technology. Results show that 1 MFC generates 1.22 mW while the optimization of the electric connection in order to achieve the maximum power results in 6.62 mW compared to the theoretical 182 mW, indicating the existence of large energy losses in the system. However, to light a LED there is not a threshold…
On the staking of miniaturized air-breathing microbial fuel cells
2018
Abstract This work focuses on the scale-up of the MFCs by miniaturization and multiplication strategy. Performances of five stacks containing 1, 2, 5, 8 and 16 MFCs were compared. Each stack was evaluated under individual, parallel and series electrical connection as well as for cascade or individual hydraulic connection. Cascade feeding mode with a tank per stack favours the COD removal when the number of MFCs in the stack increases. However, despite operating without COD limitations, the energy production was disadvantaged. By changing the feeding system of a tank per stack into an individual tank per MFC, the performance of the whole stack enhances considerably. Stacking in series can in…
Multivariate correlation measures reveal structure and strength of brain–body physiological networks at rest and during mental stress
2021
In this work, we extend to the multivariate case the classical correlation analysis used in the field of network physiology to probe dynamic interactions between organ systems in the human body. To this end, we define different correlation-based measures of the multivariate interaction (MI) within and between the brain and body subnetworks of the human physiological network, represented, respectively, by the time series of delta, theta, alpha, and beta electroencephalographic (EEG) wave amplitudes, and of heart rate, respiration amplitude, and pulse arrival time (PAT) variability. MI is computed: (i) considering all variables in the two subnetworks to evaluate overall brain–body interaction…
On the Post-Elastic Behavior of LRPH Connections
2019
The paper concerns the study of the post-elastic behavior of a recently proposed innovative device, named Limited Resistance Rigid Perfectly Plastic Hinge (LRPH). In particular, LRPH is a steel device of finite length realizing a moment connection between beam elements of a steel frame; it is designed in order to possess two main and independent requirements: its bending moment resistance must be suitably lower than the one of the connected beam element and its overall bending stiffness must be equal to that of the connected beam element characterized by the same length. In order to make the proposed device reliable, LRPH must be capable of realizing a full plastic hinge for the assigned be…