Search results for "Structural engineering"
showing 10 items of 1998 documents
Mediterranean Coastal Lagoons Review: Sites to Visit before Disappearance
2022
Coastal lagoons are an established priority habitat in the European environment because of the biological communities that inhabit them. Their origin is related to the transport of sediments from a nearby river or the movement of sands by the marine currents that produce the closure of a gulf. Therefore, they are recent geological formations, which also disappear quickly if environmental conditions change. The 37 coastal lagoons with a surface area greater than 10 km2 located in the Mediterranean basin have been identified. Fishing has been the traditional use of these lagoons, in addition to their use as a navigation harbor when they are open to the sea. Pollution, quality problems and the…
Rail freight transport and demand requirements : an analysis of attribute cut-offs through a stated preference experiment
2014
This paper analyses the choice between road and rail in Spain where rail market share for freight is still residual. Discrete choice models are estimated with data obtained through a two-phase fieldwork, thus allowing us to carry out a stated preference efficient design for each interviewee. We analyse the existence of attribute cut-offs and the presence of a segment of the population with a zero value of frequency. Our results show that ignoring the existence of cut-offs and segments of the population with polarised valuations can lead to erroneous conclusions in terms of the possibilities of rail for absorbing significant quota.
Cost analysis of the facilities deterioration in wastewater treatment plants: A dynamic approach
2019
Abstract The implementation of the Directive 91/271 / CEE resulted in the proliferation of new Wastewater Treatment Plants (WWTPs) all around Europe. These facilities, which are compound by a wide range of assets (civil works, electromechanical equipment, pipelines, etc.), are ageing and deteriorating having an impact on the efficiency of the process. It is founded that repairs and corrective maintenance costs have increased in the last years, due to the deterioration process. Therefore, the aim of the present study is to focus on the cost effects of the deterioration process of the facilities in different wastewater treatment technologies. The analysis of these impacts will allow the opera…
Analysis and optimization against buckling of beams interacting with elastic foundation
2017
We consider an infinite continuous elastic beam that interacts with linearly elastic foundation and is under compression. The problem of the beam buckling is formulated and analyzed. Then the optimization of beam against buckling is investigated. As a design variable (control function) we take the parameters of cross-section distribution of the beam from the set of periodic functions and transform the original problem of optimization of infinite beam to the corresponding problem defined at the finite interval. All investigations are on the whole founded on the analytical variational approaches and the optimal solutions are studied as a function of problems parameters. peerReviewed
Vibrations of a continuous web on elastic supports
2017
We consider an infinite, homogenous linearly elastic beam resting on a system of linearly elastic supports, as an idealized model for a paper web in the middle of a cylinder-based dryer section. We obtain closed-form analytical expressions for the eigenfrequencies and the eigenmodes. The frequencies increase as the support rigidity is increased. Each frequency is bounded from above by the solution with absolutely rigid supports, and from below by the solution in the limit of vanishing support rigidity. Thus in a real system, the natural frequencies will be lower than predicted by commonly used models with rigid supports. peerReviewed
Reliable measures of plastic deformations for elastic plastic structures in shakedown conditions
2020
A new formulation for evaluating reliable measures of the plastic deformations occurring in the transient phase of a structure in shakedown conditions is proposed. The structure is thought as constituted by elastic perfectly plastic material and subjected to a combination of fixed and cyclic loads. The proposed formulation consists in the search for the optimal plastic strain field that minimize a suitable objective function defining a strain energy measure related to the plastic strains at the shakedown limit. The typical self-stress field can be obtained as the elastic structural response to an assigned plastic strain field respecting appropriate ductility limits for the material. Without…
Performance Comparison of Electrical Motors equipped with slightly Asymmetrical Windings
2019
This paper presents a comparison between the performances of electrical machines equipped with slightly asymmetrical windings. More in detail, by modifying the stator geometry of an Interior Permanent Magnet Synchronous Machine equipped with a symmetrical winding configuration, other two slightly asymmetrical winding topologies are obtained. The three models are, then, analyzed by means of a finite element method (FEM) and the related results are compared in terms of cogging torque, static characteristics and leakage factor. The obtained results demonstrate that the adoption of slightly asymmetrical windings could be an interesting alternative solution during the design stage of electrical …
Bipolar electrolysis for tritium recovery from weakly active tritiated water
2001
Abstract Detritiation facilities produce low activity tritiated water from which tritium cannot be recovered. Bipolar electrolysis, based on the electrochemical permeation of hydrogen and its isotopes through Pd–Ag alloy membranes, allows tritiated water enrichment together with negligible gaseous tritium release. Our purpose is to enrich water from 500 Ci/l (1.85×1013 Bq/l) to more than 2000 Ci/l (7.40×1013 Bq/l). We first describe the principle of bipolar electrolysis and its application to isotopic enrichment. The experimental part of this work consists of the determination of the isotopic separation factors. From these experimental values, we simulated the working of an operational cell…
Layer-wise and equivalent single layer models for smart multilayered plates
2014
Layer-wise and equivalent single layer plate models for magneto-electro-elastic multiphysics laminates are presented in a unified framework. They are based on variable kinematics and quasi-static behavior of the electromagnetic fields. The electromagnetic state of each single layer is preliminary determined by solving the corresponding governing equations coupled with the proper interface continuity and external boundary conditions. By so doing, the electromagnetic state is condensed into the plate kinematics and the layer governing equations are inferred by the principle of virtual displacements. This approach identifies effective mechanical layers, which are kinematically equivalent to th…
An integrated structural health monitoring system based on electromechanical impedance and guided ultrasonic waves
2015
We propose a structural health monitoring (SHM) paradigm based on the simultaneous use of ultrasounds and electromechanical impedance (EMI) to monitor waveguides. Methods based on the propagation of guided ultrasonic waves (GUWs) are increasingly used in all those SHM applications that benefit from built-in transduction, moderately large inspection ranges, and high sensitivity to small flaws. Meantime, impedance-based SHM promises to adequately assess locally the structural integrity of simple waveguides and complex structures such as bolted connections. As both methods utilize piezoelectric transducers bonded or embedded to the structure of interest, this paper describes a unified SHM para…