IDEA (Innovative Detector for Electron–positron Accelerators) is a detector concept designed for a future leptonic collider operating as a Higgs factory. It is based on innovative detector ...technologies developed over years of R&D. In September 2018, prototypes of the proposed sub-detectors have been tested for the first time on a beam line at CERN. The preliminary results from this test of a full slice of the IDEA detector and standalone measurements of dual read-out calorimeter prototypes are presented.
A 66 m-tall masonry chimney, dating back to the end of the XIX century, is analyzed. The chimney is no longer in service, and is part of a company town located in northern Italy, which is included in ...the UNESCO World Heritage List. The chimney has a double wall up to a certain height, and is single-walled in the remaining part. In the lower part, the two walls are connected by vertical ribs and horizontal diaphragms. The chimney exhibits several faults (cracks, tilt), which were accurately detected by means of a direct survey. Aim of this research is the identification of the possible origin of the cracks, which can be helpful in the definition of future repair interventions. A detailed finite element model of the chimney is developed. Both wind actions and thermal changes induced by combustion fumes are taken into account. After excluding that wind can have originated cracks, attention is focused on thermal strains. The presence of most cracks can be actually motivated by thermal effects, provided that the anisotropic strength of brickwork is taken into account. Accordingly, most cracks are likely to have formed when the chimney was operational. Appropriate repairs can ensure that the disused chimney will remain safe, as the development of new, significant cracks can be excluded. The conclusion of this research can be extended to other coeval chimneys of similar geometry.
The structural behavior of a masonry farmhouse exhibiting several faults is investigated. The building has an irregular plan, which is probably the outcome of different construction phases; the ...oldest part dates back to the seventeenth century. The building underwent several interventions of consolidation, including the addition of ties, a buttress, and micropiles. Despite these interventions, the building is still heavily damaged, with vertical and inclined deep cracks. A static monitoring system was installed to track the major cracks for a duration of 18 months: some were found to be still propagating. Interpretation of the crack pattern allows the causes that originated the main faults, including changes in geometry, to be better understood. An in-depth analysis on the building also allows some geometric anomalies to be highlighted. These anomalies can probably be traced back to the different construction phases, and locally weaken the structural strength. A detailed finite element model, taking the properties of the different materials into account, was developed. The main cracks existing in the building were also included in the model. Structural analyses were carried out taking gravity loads, ground settlements, and possible seismic actions into account. The tensile stresses in some parts of the building are found to be sufficiently high to induce further crack growth. The numerical results are used to propose simple retrofitting strategies
•Original application of topology optimization to the design of masonry blocks.•Combined optimization of thermal and mechanical performances of masonry blocks.•Achievement of non-trivial block ...layouts, depending on the design constraints.
The problem of maximizing the thermal insulation of buildings is dealt with, by determining the geometry of masonry blocks that minimizes the transmittance of any wall. Assuming the heat flux to be uniform across the wall surfaces, topology optimization is employed to define the layout of the block section. Constraints on the block stiffness are also prescribed. The presence of holes of given shape in any prescribed position and other technological constraints can be easily embodied in the optimization procedure. The effect of the design constraints on the optimal layout of the blocks is investigated. The thermal efficiency of the optimized units is also compared with that of commercially available blocks.
A numerical model is presented, based on the finite element method in its displacement formulation, aimed at the analysis of the representative volume element (RVE) of composites reinforced by a ...regular array of long, parallel fibers, subjected to any 3-D macroscopic stress or strain state. Special finite elements are formulated, which are capable of describing three-dimensional deformation modes associated with strain fields invariant along the fiber axis. Periodicity boundary conditions at the sides of the RVE complete the kinematic formulation. The model is applied to metal–matrix composites, assuming an elastic–perfectly plastic behaviour for both phases; the compatibility matrix of the finite elements is modified, according to proposals of other authors, to avoid locking phenomena near the fully plastic range. Some numerical applications are shown to illustrate the possibility of employing the model to predict the macroscopic response of metal–matrix composites in the non-linear field and up to failure. Comparisons with analytical and experimental results available in the literature testify the reliability of the model estimates.
IDEA (Innovative Detector for an Electron–positron Accelerator) is a general-purpose detector concept, designed to study electron–positron collisions in a wide energy range in a very large circular ...leptonic collider. Its drift chamber is designed to provide an efficient tracking, a high precision momentum measurement and an excellent particle identification by exploiting the application of the cluster counting technique. To investigate the potential of the cluster counting techniques on physics events, a simulation of the ionization cluster generation is needed, therefore we developed an algorithm which can use the energy deposit information provided by the Geant4 toolkit to reproduce, in a fast and convenient way, the cluster number and cluster size distributions. The results obtained confirm that the cluster counting technique allows to reach a resolution two times better than the traditional dE/dx method. A beam test has been performed during November 2021 at CERN on the H8 beam line to validate the simulations results, to define the limiting effects for a fully efficient cluster counting and to count the number of electron clusters released by an ionizing track at a fixed βγ as a function of the track angle. The simulation and the beam test results will be described briefly in this issue.
A homogenization technique applied in conjunction with limit analysis theory allows the prediction of the macroscopic strength of fiber composites as a function of the strength properties of the ...phases (i.e. fiber, matrix and interface). Emphasis is placed here on the uniaxial strength, for which bounds based on static and kinematic approaches are proposed. Special attention is devoted to the influence of the matrix, which is presumed to be polymeric and complying with Drucker-Prager, Mohr-Coulomb or a parabolic type criterion. Also the limited strength of the fiber-matrix interface is accounted for through the introduction of a Mohr-Coulomb type strength criterion. Analytical equations describing the dependence of the macroscopic strength of the composite on the orientation of the applied stress with respect to the fibers are proposed. The parameters required to define the model are limited in number and possess a clear mechanical meaning. Comparisons with experimental data available in the literature prove quite satisfactory.
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