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Multiple fault parameter estimation of a fully assembled turbogenerator system

Lal M.

Archive of Mechanical Engineering

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2018

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Vol. LXV, nr 2

233--252

EN

The present article investigates the dynamic behavior of a fully assembled turbogenerator system inﬂuenced by misalignment. In the past, most of the researchers have neglected the foundation ﬂexibility in the turbogenerator systems in their study, to overcome this modelling error a more realistic model of a turbogenerator system has been attempted by considering ﬂexible shafts, ﬂexiblecoupling, ﬂexible bearings and ﬂexible foundation. Equations of motion for fully assembled turbogenerator system including ﬂexible foundations have been derived by using ﬁnite element method. The methodology developed based on least squares technique requires forced response information to quantify the bearing–coupling–foundation dynamic parameters of the system associated with diﬀerent faults along with residual unbalances.The proposed methodology is tested for the various level of measurement noise and modelling error in the system parameters, i.e., 5% deviation in E (modulus of elasticity) and ρ (density), respectively, for robustness of the algorithm. In a practical sense, the condition analyzed in the present article relates to the identiﬁcation of misalignment and other dynamic parameters viz. bearing and residual unbalance in a rotor integrated with ﬂexible foundation.

2

Estimation of speed dependent fault parameters in a coupled rotor-bearing system

Lal M., Satapathy M.

Archive of Mechanical Engineering

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2018

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Vol. LXV, nr 3

327--347

EN

In rotating machineries, misalignment is considered as the second most major cause of failure after unbalance. In this article, model-based multiple fault identiﬁcation technique is presented to estimate speed-dependent coupling misalignment and bearing dynamic parameters in addition with speed independent residual unbalances. For brevity in analysis, a simple coupled rotor bearing system is considered and analytical approach is used to develop the identiﬁcation algorithm. Equations of motion ingeneralized co-ordinates are derived with the help of Lagrange’s equation and least squares ﬁtting approach is used to estimate the speed-dependent fault parameters. Present identiﬁcation algorithm requires independent sets of forced response data which are generated with the help of diﬀerent sets of trial unbalances. To avoid/suppress the ill-conditioning of regression equation, independent sets of forced response data are obtained by rotating the rotor in clock-wise and counter clock-wise directions, alternatively. Robustness of algorithm is checked for diﬀerent levels of measurement noise.

3

Enantioseparation of amino alcohols by reversed-phase high-performance liquid chromatography using cyanuric chloride-based chiral derivatizing reagents having amino acids and their amides as chiral auxiliaries

Bhushan R., Lal M.

Acta Chromatographica

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2014

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Vol. 26, no. 3

413--427

EN

A high-performance liquid chromatographic (HPLC) method was developed for enantioresolution of amino alcohols using an indirect approach. Two sets of chiral derivatizing reagents (CDRs) having amino acids (CDRs 1–4; set A) and their amides (CDRs 5–8; set B) as chiral auxiliaries in cyanuric chloride (CC) moiety were synthesized and characterized. Diastereomers of eight amino alcohols were synthesized, under microwave irradiation, using each of the eight CDRs. The resulting diastereomers were separated by reversed-phase high-performance liquid chromatography (RP-HPLC) using C18 column and eluting mixtures of acetonitrile with aqueous trifluoroacetic acid (aq.TFA) in a linear gradient (45 min) with UV detection at 230 nm. The results (in terms of resolution Rs and retention factor k) obtained for the two sets of diastereomers were compared among themselves and among the two groups. The effects of chiral auxiliaries (in terms of acid and amides variants), constituting CDRs, on separation were also evaluated. The elution order for the diastereomers was determined. The separation method was validated for limit of detection (LOD), linearity, accuracy, precision, and recovery.