Search results for "Rotor"
showing 10 items of 129 documents
ROBUST CONTROL FOR A SUSPENDED ROTATING SHAFT BY RADIAL ACTIVE MAGNETIC BEARINGS
2011
This paper shows a comparison based on dynamic behaviour of a rotating shaft when it is suspended by 4-axis active magnetic bearings under several control systems. The control systems used are μ-synthesis, loop shaping design procedure and Sub(H∞) robust control with the introduction of uncertainties on position and current gains of the actuators. Each of these controllers is characterized by four input signals and four output signals and the introduction of uncertainties on displacement gain and current gain is due to torn and worn of the components during the time, which can lead the entire system to instability phenomena. The comparison of the performances is obtained through the introdu…
INFLUENZA SUL COMPORTAMENTO DINAMICO DI UN ROTORE SOSPESO ATTRAVERSO CUSCINETTI MAGNETICI ATTIVI MEDIANTE μ-SYNTHESIS E LOOP-SHAPING DESIGN
2011
In questo lavoro viene effettuato un confronto sul comportamento dinamico di un albero rotante quando è sospeso attraverso un sistema di due cuscinetti magnetici ciascuno costituito da due assi. Le sospensione magnetica attiva è ottenuta elaborando due diversi sistemi di controllo che realizzano la stabilità del rotore conferendo a quest’ultimo delle prestazioni robuste nel mantenimento degli spostamenti entro certi margini prestabiliti. Ognuno di questi sistemi di controllo è caratterizzato da otto ingressi e quattro uscite con la presenza di incertezze sul guadagno spostamento e guadagno di corrente; ciò è giustificato dal semplice fatto che gli apparati elettronici possono usurarsi con i…
Geometric Algebra Rotors for Sub-Symbolic Coding of Natural Language Sentences
2007
A sub-symbolic encoding methodology for natural language sentences is presented. The procedure is based on the creation of an LSA-inspired semantic space and associates rotation operators derived from Geometric Algebra to word bigrams of the sentence. The operators are subsequently applied to an orthonormal standard basis of the created semantic space according to the order in which words appear in the sentence. The final rotated basis is then coded as a vector and its orthogonal part constitutes the sub-symbolic coding of the sentence. Preliminary experimental results for a classification task, compared with the traditional LSA methodology, show the effectiveness of the approach.
La Sicilia del Design
2009
Se non si hanno parole migliori è bene adoperare quelle già scritte, specie se costruite dalle mani di Gesualdo Bufalino che con lucido e spietato amore disegna la sua terra. Delle tante Sicilie mi piacerebbe raccontarvi quella che pigramente, per non tradire del tutto la sua natura, si muove verso possibili scenari in cui il design, con i suoi tanti nomi, può dive n i re uno strumento per valorizzare il territorio denso di patrimoni, come quello dei beni culturali, dell’artigianato, dell’enogastronomia, patrimoni ricchi e altrettanto scarsamente valorizzati e comunicati. If you do not have better words it is good to use those already written, especially if built by the hands of Gesualdo Bu…
Analysis of Stray Flux Spectral Components in Induction Machines under Rotor Bar Breakages at Various Locations
2018
Induction machines under rotor electrical faults have been subjected to intensive research over the years. It is not only the nature of the fault that makes it important to study, but also the differences observed regarding this fault's effect on the motor's conditions. One of these conditions is the rotor bar breakages at non adjacent positions, which has drawn the attention of researchers due to the false negative diagnostic alarms that may be caused. In this paper, a novel approach is presented aiming to reliably detect this type of fault condition. The proposed method is based on the analysis of specific subcomponents of the stray flux over time. The analysis is implemented on an indust…
Small Wind Turbines: Specification, Design, and Economic Evaluation
2016
In this work, we consider various aspects of small wind turbines' (SWTs) design and operation. First, an extensive literature study is presented by considering SWTs specification, market statistics, the smart grid, and the prosumer concepts as well as the most important parameters affecting the efficiency of wind turbines. Then, both the literature review and series of coupled numerical simulations investigating impact of the chosen design solutions on small wind turbine operation are performed. It allowed objective evaluation of different design approaches, which in turn enabled the systematic identification of actual limitations as well as the opportunities for specific design solutions o…
A Switchable Molecular Rotator: Neutron Spectroscopy Study on a Polymeric Spin-Crossover Compound
2012
A quasielastic neutron scattering and solid-state 2H NMR spectroscopy study of the polymeric spin-crossover compound {Fe(pyrazine)[Pt(CN) 4]} shows that the switching of the rotation of a molecular fragment-the pyrazine ligand-occurs in association with the change of spin state. The rotation switching was examined on a wide time scale (10 -13-10 -3 s) by both techniques, which clearly demonstrated the combination between molecular rotation and spin-crossover transition under external stimuli (temperature and chemical). The pyrazine rings are seen to perform a 4-fold jump motion about the coordinating nitrogen axis in the high-spin state. In the low-spin state, however, the motion is suppres…
Diagnosis of inverter-fed induction motors in short time windows using physics-assisted deep learning framework
2019
This article presents a framework for accurate fault diagnostics in inverter-fed induction machinery operating under variable speed and load conditions within very short time windows. Condition indicators based on fault characteristic frequencies observed over the extended Park's vector modulus are fused with deep features extracted using stacked autoencoders to generate a multidimensional feature space for fault classification using support vector machine. The proposed approach is demonstrated in a laboratory setup to detect the most commonly occurring faults, namely, the stator turns fault, broken rotor bars fault and bearing fault with an accuracy > 98% within a short time window of 2–3 …
Active magnetic bearing design study
2012
The purpose of this paper is to propose a useful method to implement active magnetic bearings (AMBs) on an existing rotating shaft which rotates on conventional bearings. This is feasible if AMBs can produce the same reaction loads of conventional ones and if the size of vane is large enough to host an AMB. As this substitution could offer some difficulties due to the different size between magnetic bearings and conventional ones, a set of equations are performed to show that a variation of some parameters can solve this problem. The journal ratio is the geometrical parameter introduced to develop the present analysis. The variation of journal ratio does not produce a variation of the pole…
On the Effect of Slotted Blades on Savonius Wind Generator Performances by CFD Analysis
2012
In this paper a new bucket configuration for Savonius wind generator is proposed. With the aim to increase the effect of the overlap ratio RS on the wind turbine performances and to increase the amount of lift force able to produce torque and power, slotted blades are investigated by means of the Computational Fluid Dynamics analysis. The numerical analyses are performed by Comsol Multiphysics® and the results obtained for a Savonius wind turbine with overlap only are compared to numerical and experimental benchmarks. Parametric analyses are performed, for fixed overlap ratio, by varying the slot angle β and the results show that for low angle β the Savonius rotor exploits improved performa…