Induction Machine Stator Fault Tracking using the Growing Curvilinear Component Analysis

Detection of stator-based faults in Induction Machines (IMs) can be carried out in numerous ways. In particular, the shorted turns in stator windings of IM are among the most common faults in the industry. As a matter of fact, most IMs come with pre-installed current sensors for the purpose of control and protection. At this aim, using only the stator current for fault detection has become a recent trend nowadays as it is much cheaper than installing additional sensors. The three-phase stator current signatures have been used in this study to observe the effect of stator inter-turn fault with respect to the healthy condition of the IM. The pre-processing of the healthy and faulty current signatures has been done via the in-built DSP module of dSPACE after which, these current signatures are passed into the MATLAB® software for further analysis using AI techniques. The authors present a Growing Curvilinear Component Analysis (GCCA) neural network that is capable of detecting and follow the evolution of the stator fault using the stator current signature, making online fault detection possible. For this purpose, a topological manifold analysis is carried out to study the fault evolution, which is a fundamental step for calibrating the GCCA neural network. The effectiveness of the proposed method has been verified experimentally

Positive and negative mood in the elderly: the ZENITH study

n/

The immune system and the impact of zinc during aging

The trace element zinc is essential for the immune system, and zinc deficiency affects multiple aspects of innate and adaptive immunity. There are remarkable parallels in the immunological changes during aging and zinc deficiency, including a reduction in the activity of the thymus and thymic hormones, a shift of the T helper cell balance toward T helper type 2 cells, decreased response to vaccination, and impaired functions of innate immune cells. Many studies confirm a decline of zinc levels with age. Most of these studies do not classify the majority of elderly as zinc deficient, but even marginal zinc deprivation can affect immune function. Consequently, oral zinc supplementation demonstrates the potential to improve immunity and efficiently downregulates chronic inflammatory responses in the elderly. These data indicate that a wide prevalence of marginal zinc deficiency in elderly people may contribute to immunosenescence

An electron microscopy study of graphite growth in nodular cast irons

Growth of graphite during solidification and high-temperature solid-state transformation has been investigated in samples cut out from a thin-wall casting which solidified partly in the stable (iron–graphite) and partly in the metastable (iron–cementite) systems. Transmission electron microscopy has been used to characterize graphite nodules in as-cast state and in samples having been fully graphitized at various temperatures in the austenite field. Nodules in the as-cast material show a twofold structure characterized by an inner zone where graphite is disoriented and an outer zone where it is well crystallized. In heat-treated samples, graphite nodules consist of well-crystallized sectors radiating from the nucleus. These observations suggest that the disoriented zone appears because of mechanical deformation when the liquid contracts during its solidification in the metastable system. During heat-treatment, the graphite in this zone recrystallizes. In turn, it can be concluded that nodular graphite growth mechanism is the same during solidification and solid-state transformatio

Single-phase axial flux claw pole motor for high efficiency applications

The paper deals with the analysis of a new type of single phase claw pole permanent motor with single side axial flux configuration. The compact structure and the adoption of advanced materials are favorable for the use in high speed ventilation and pumping systems, where efficiency represents a key issue. A preliminary analysis is carried out by means of 3D FE magnetostatic simulations to check the main electromagnetic performances at a predefined steady state operation. As a result, a skewed configuration is defined, yielding an appreciable improvement with respect to the initial one. Then a mathematical model is developed to simulate the actual dynamic operation, taking into account the nonlinearity of the electromagnetic parameters. The results obtained confirm the motor suitability to drive low rated loads with high efficiency and constant power operation in a wide speed range

Network approach for the analysis of the irreversible deformation of solids with soft heterogeneities

We introduce the concept of shear band network (SBN) in ductile solids containing soft particles to investigate their irreversible deformation. Drawing on network science tools, we show that the evolution of the SBN explains the material strength at the coarse scale. To gain physical understanding of the activation order of the SBN links during tensile loading, we develop an analytical model based on the continuum theory of irreversible deformation. The results are used to construct an efficient, parameter-free indicator of the material strength that is solely based on the particle size and spatial distribution, thus proving that network science can advance the understanding of strength mechanisms in ductile solids