Rotor bar pre-fault detection in the squirrel cage induction motors

The paper deals with a diagnosis technique to detect and monitor incipient faults in the rotor bars of squirrel gage induction motors. The failure mode analysis is performed monitoring the motor axial vibrations. To accomplish the task, the authors present a mathematical model that allows relating the occurrence and the severity of the faults to the presence and the magnitude of some frequency components of the axial vibration spectrum. To validate the proposed approach, the results obtained by applying the mathematical model are compared with the ones obtained by experimental tests done on both healthy and faulty motors

Voltage source inverters: an easy approach for fast fault detection

Peer Reviewe

Type-1 (CB1) cannabinoid receptor promotes neuronal differentiation and maturation of neural stem cells .

Neural stem cells (NSCs) are self-renewing cells that can differentiate into multiple neural lineages and repopulate regions of the brain after injury. We have investigated the role of endocannabinoids (eCBs), endogenous cues that modulate neuronal functions including neurogenesis, and their receptors CB1 and CB2 in mouse NSCs. Real-time PCR and Western blot analyses indicated that CB1 is present at higher levels than CB2 in NSCs. The eCB anandamide (AEA) or the CB1-specific agonist ACEA enhanced NSC differentiation into neurons, but not astrocytes and oligodendrocytes, whereas the CB2-specific agonist JWH133 was ineffective. Conversely, the effect of AEA was inhibited by CB1, but not CB2, antagonist, corroborating the specificity of the response. CB1 activation also enhanced maturation of neurons, as indicated by morphometric analysis of neurites. CB1 stimulation caused long-term inhibition of the ERK1/2 pathway. Consistently, pharmacological inhibition of the ERK1/2 pathway recapitulated the effects exerted by CB1 activation on neuronal differentiation and maturation. Lastly, gene array profiling showed that CB1 activation augmented the expression of genes involved in neuronal differentiation while decreasing that of stemness genes. These results highlight the role of CB1 in the regulation of NSC fate and suggest that its activation may represent a pro-neuronal differentiation signal

Conceptualizing and measuring “industry resilience”: Composite indicators for postshock industrial policy decision-making

Can resilience be a relevant concept for industrial policy? Resilience is usually described as the ability of a socioeconomic system to recover from unexpected shocks. While this concept has caught the attention of regional economics researchers seeking to understand the different patterns behind regional recovery after a disruption, it is increasingly recognized that resilience can have policy-relevant conceptual applications in many other regards. In this paper, we apply it to industries and define the “industry resilience” concept and measurements. Our contribution is twofold. Theoretically, we frame industry resilience as a useful conceptual framework for policy-making to support the selection of industrial policy targets that are more capable of recovering after unexpected shocks. In addition, industry resilience can mitigate government failures by supporting decision-makers in promoting both economically and socially sustainable structural change. Methodologically, building on post-2008 U.S. data, we develop two composite indicators (CIs) to separately analyze quantitative and qualitative postshock variations in sectoral employment. Such CIs support policy-makers in visualizing sectoral performances dynamically and multidimensionally and can be used to compare each sector both to other sectors and to its counterfactual. Our results highlight that sectors react heterogeneously to shocks. This points to the relevance of tailoring vertical industrial policies according to sector features and the aims of industrial policy initiatives

Characterization of the parameters of interior permanent magnet synchronous motors for a loss model algorithm

The paper provides the results of a detailed experimental study on the variations of the characteristics of an interior permanent magnet synchronous motor, when load, speed and/or magnetization conditions vary. In particular, the characterization is carried out by assessing, for several working conditions, the motor parameters that influence its efficiency. From the knowledge of the variability of these parameters, it is possible to develop a dynamic model of the motor, which accurately describes its behaviour and allows estimating the power losses for whatever speed and load. In order to validate the model, the values of the power losses obtained by using the model are compared with the values measured with experimental tests. The study shows that it is possible to maximize the motor efficiency just acting on the direct axis current component and, therefore, it can be considered a first step towards the definition of a loss model algorithm for a control drive system able to minimize in real-time the power losses of the motor

Closed-loop bandwidth impact on MVSA for rotor broken bar diagnosis in IRFOC double squirrel cage induction motor drives

This paper investigates the detectability of rotor broken bars in indirect rotor flux oriented control (IRFOC) for variable speed double cage induction motor drives, using vibration signature analysis techniques. The Impact of the closed loop control system cannot be neglected when the detection of rotor asymmetries in the machine is based on the signature analysis of electrical or mechanical variables. Therefore, the investigation of rotor fault components for different bandwidths of closed-loop regulators is necessary to evaluate its relevance in the above listed variables. This paper investigates the impact of the control system on relevance of the fault components computed from axial and radial vibration signals. Experimental results show the validity of this impact, and more specifically, the bandwidth PI regulators. Due to its relevance, axial vibration analysis shows a more robust fault signature, under the control impact, in separating healthy from rotor bar breakage in double squirrel cage induction motors

Quantitative Rotor Broken Bar Evaluation in Double Squirrel Cage Induction Machines under Dynamic Operating Conditions

Advanced monitoring techniques leading to fault diagnosis and prediction of induction machine faults, operating under non-stationary conditions have gained strength because of its considerable influence on the operational continuation of many industrial rocesses. In case of rotor broken bars, fault detection based on sideband components issued from currents, flux, instantaneous control or power signals under different load conditions, may fail due to the presence of inter-bar currents that reduce the degree of rotor asymmetry, especially for double squirrel cage induction motors. But the produced core vibrations in the axial direction, can be investigated to overcome the limitation of the classical technique using appropriate time-frequency analysis for these purposes. Unlike previous approaches, the presented technique is based on optimized use of the Discrete wavelet transform to overcome the limitation of classical frequency approaches under non-stationary operating conditions. The developed approach is best suited for automotive or high power traction systems, in which safe-operating and availability are mandatory. Experimental results are provided, showing the validity of the investigated technique, leading to an effective diagnosis procedure for incipient rotor broken bars in double or single cage induction machines under dynamic operating conditions

Serum cardiac troponin I concentration in dogs with precapillary and postcapillary pulmonary hypertension.

Background: Pulmonary hypertension (PH) is a disease condition leading to right\u2010sided cardiac hypertrophy and, eventually, right\u2010sided heart failure. Cardiac troponin I (cTnI) is a circulating biomarker of cardiac damage. Hypothesis: Myocardial damage can occur in dogs with precapillary and postcapillary PH. Animals: One hundred and thirty\u2010three dogs were examined: 26 healthy controls, 42 dogs with mitral valve disease (MVD) without PH, 48 dogs with pulmonary hypertension associated with mitral valve disease (PH\u2010MVD), and 17 dogs with precapillary PH. Methods: Prospective, observational study. Serum cTnI concentration was measured with a commercially available immunoassay and results were compared between groups. Results: Median cTnI was 0.10\u2003ng/mL (range 0.10\u20130.17\u2003ng/mL) in healthy dogs. Compared with the healthy population, median serum cTnI concentration was increased in dogs with precapillary PH (0.25\u2003ng/mL; range 0.10\u20131.9\u2003ng/mL; P < .001) and in dogs with PH\u2010MVD (0.21\u2003ng/mL; range 0.10\u20132.10\u2003ng/mL; P < .001). Median serum cTnI concentration of dogs with MVD (0.12\u2003ng/mL; range 0.10\u20131.00\u2003ng/mL) was not significantly different compared with control group and dogs with PH\u2010MVD. In dogs with MVD and PH\u2010MVD, only the subgroup with decompensated PH\u2010MVD had significantly higher cTnI concentration compared with dogs with compensated MVD and PH\u2010MVD. Serum cTnI concentration showed significant modest positive correlations with the calculated pulmonary artery systolic pressure in dogs with PH and some echocardiographic indices in dogs with MVD and PH\u2010MVD. Conclusions and Clinical Importance: Serum cTnI is high in dogs with either precapillary and postcapillary PH. Myocardial damage in dogs with postcapillary PH is likely the consequence of increased severity of MVD

Vibration signature analysis for rotor broken bar diagnosis in double cage induction motor drives

The paper investigates the diagnosis of rotor broken bars in field oriented controlled (FOC) double cage induction motor drives, using current and vibration signature analysis techniques. The Impact of the closed loop control system cannot be neglected when the detection of asymmetries in the machine are based on the signature analysis of electrical variables. The proposed diagnosis approach is based on optimized use of wavelet analysis by a pre-processing of phase current or axial/radial vibration signals. Thus, the time evolution of the tracked rotor fault components can be effectively analyzed. This paper shows also the relevance of the fault components computed from axial vibration signal in comparison to those coming from phase current and radial vibration signals. Cyclic fault quantification, issued from the wavelet analysis, has been introduced for accurate rotor fault detection. Experimental results show the validity of the proposed technique, leading to an effective diagnosis procedure for rotor broken bar in double cage induction motor

Diagnosis of mechanical unbalance for double cage induction motor load in time-varying conditions based on motor vibration signature analysis

This paper investigates the detectability of mechanical unbalance in double cage induction motor load using motor vibration signature analysis technique. Rotor imbalances induce specific harmonic components in electrical, electromagnetical, and mechanical quantities. Harmonic components characteristic of this category of rotor faults, issued from vibration signals analysis, are closely related to rotating speed of the rotor, which complicates its detection under non-stationary operating conditions of the motor. Firstly, experimental results were performed first under healthy and mechanical load unbalance cases, for different load levels under steady-state operating conditions to evaluate the sensitivity of motor axial vibration signature analysis (MAVSA) and motor radial vibration signature analysis (MRVSA) techniques. Secondly, and in order to overcome the limitations of the FFT analysis in time-varying conditions, a simple and effective method based on advanced use of wavelet analysis is proposed, that allows the diagnosis of mechanical load unbalance for a double cage induction machine operating under non-stationary conditions. Experimental tests were conducted for these purposes showing the effectiveness of the presented technique under time-varying operating conditions