Search results for "Mechanical engineering"
showing 10 items of 4245 documents
The Gantry-Tau parallel kinematic machine-kinematic and elastodynamic design optimisation
2011
Pubished version of an article in the journal: Meccanica. Also available from the publisher at: http://dx.doi.org/10.1007/s11012-010-9394-9 One of the main advantages of the Gantry-Tau machine is a large accessible workspace/footprint ratio compared to many other parallel machines. The optimal kinematic, elastostatic and elastodynamic design parameters of the machine are still difficult to calculate and this paper introduces an optimisation scheme based on the geometric and functional dependencies to define the workspace and first resonance frequency. This method assumes that each link and universal joint can be described by a mass-spring-damper model and calculates the transfer function fr…
Seismic evaluation of ordinary RC buildings retrofitted with externally bonded FRPs using a reliability-based approach
2020
International audience; Despite the extensive literature on reinforced concrete (RC) members retrofitted with fiberreinforced polymer (FRP) composites, few studies have employed a reliability-based approach to evaluate the seismic performance of RC buildings in terms of their collapse capacity and ductility. In this study, the performance of a poorly-confined RC building structure is investigated for different FRP retrofitting schemes using different configurations and combinations of wrapping and flange-bonded FRPs, as two well-established techniques. A nonlinear pushover analysis is then implemented with a computational reliability analysis based on Latin Hypercube Sampling (LHS) to deter…
A Damage Identification Approach for Offshore Jacket Platforms Using Partial Modal Results and Artificial Neural Networks
2018
This paper presents a damage identification method for offshore jacket platforms using partially measured modal results and based on artificial intelligence neural networks. Damage identification indices are first proposed combining information of six modal results and natural frequencies. Then, finite element models are established, and damages in structural members are assumed by reducing the structural elastic modulus. From the finite element analysis for a training sample, both the damage identification indices and the damages are obtained, and neural networks are trained. These trained networks are further tested and used for damage prediction of structural members. The calculation res…
A Novel Solution to Find the Dynamic Response of an Euler–Bernoulli Beam Fitted with Intraspan TMDs under Poisson Type Loading
2020
This contribution considers a virtual experiment on the vibrational response of rail and road bridges equipped with smart devices in the form of damping elements to mitigate vibrations. The internal damping of the bridge is considered a discontinuity that contain a dashpot. Exact complex eigenvalues and eigenfunctions are derived from a characteristic equation built as the determinant of a 4 x 4 matrix
Numerical and experimental analysis of a high innovative hydrofoil
2020
The hydrofoil is a craft where the weight is entirely supported by the lift generated by the submerged part of wings. The particular structure of the craft requires a thorough study of the architecture of the hull, whose structure differs from others high speed vessels since the lift on wing surfaces are transmitted to the hull in limited areas (wing attacks). The authors have developed a research to optimize geometry of hull and wing system on a hydrofoil capable to carry 250 passengers at a speed of 35 knots, operating among Sicilian island. The principal goals of the new hydrofoil concern both the fuel reduction that the improvement of the comfort in terms of seakeeping and levels of aco…
Energy efficient optimisation for large‐scale multiple‐antenna system with WPT
2018
In this study, an energy-efficient optimisation scheme for a large-scale multiple-antenna system with wireless power transfer (WPT) is presented. In the considered system, the user is charged by a base station with a large number of antennas via downlink WPT and then utilises the received power to carry out uplink data transmission. Novel antenna selection, time allocation and power allocation schemes are presented to optimise the energy efficiency of the overall system. In addition, the authors also consider channel state information cannot be perfectly obtained when designing the resource allocation schemes. The non-linear fractional programming-based algorithm is utilised to address the …
Diagnosis of Sensor Faults in PMSM and Drive System Based on Structural Analysis
2021
This paper presents a model-based fault diagnosis method to detect sensor faults in permanent magnet synchronous motor (PMSM) drives based on structural analysis technique. The structural model is built based on the dynamic model of the PMSM in matrix form, including unknown variables, known variables, and faults. The Dulmage-Mendelsohn (DM) decomposition is applied to evaluate the redundancy of the model and obtain redundant testable sub-models. These testable redundant sub-models are used to form residuals to observe the system state, and distinguish between healthy and faulty conditions. This work investigates faults in eleven sensors in a PMSM drive, thus nine structured residuals are d…
The use of slightly asymmetrical windings for rotating electrical machines
2018
Historically, asymmetrical windings in electrical machines have been rarely used and only for specified needs, because the adoption of symmetrical configurations has always been considered the only solution during the design stage of electrical machines. The aim of this work is to demonstrate with several examples that the use of slightly asymmetrical windings can be a reasonable choice and, in certain cases, a favorable option during the machine design stage, allowing the possibility of selecting a wider range of slot/pole number combinations, without affecting the performances of the machines. More in detail, an interior permanent magnet synchronous machine equipped with a symmetrical 3-p…
Designing an innovative system for sea wave utilization
2018
For the sea wave energy exploitation, the department of Energy of Palermo University is investigating a new approach based on the mechanical motion conversion from a linear motion into a unidirectional rotary motion. This mechanical output can be used to run alternators, producing electrical power with a very simplified energy conversion chain. First preliminary tests have been realized in laboratory using a small-scale prototype.
A simple method for the design of hybrid electric power-split cvts: A case study
2018
A brief parametric method for the preliminary design of hybrid electric Power-Split CVTs is performed. The desired torque-speed characteristic is obtained, and general control and optimization criteria are introduced in order to minimize the size of the required electric machines. The optimization is performed by mean of scheme-independent functional parameters, while a specific constructive design is proposed only later, along with possible full electric operations.