A New Formulation of Maxwell’s Equations

In this paper, new forms of Maxwell’s equations in vector and scalar variants are presented. The new forms are based on the use of Gauss’s theorem for magnetic induction and electrical induction. The equations are formulated in both differential and integral forms. In particular, the new forms of the equations relate to the non-stationary expressions and their integral identities. The indicated methodology enables a thorough analysis of non-stationary boundary conditions on the behavior of electromagnetic fields in multiple continuous regions. It can be used both for qualitative analysis and in numerical methods (control volume method) and optimization. The last Section introduces an application to equations of magnetic fluid in both differential and integral forms.

Fault Severity Sensing for Intelligent Remote Diagnosis in Electrical Induction Machines

Electrical induction machines are widely used in the modern wind power production. As their repair cost is important and since their down-time leads to significant income loss, increasing their reliability and optimizing their proactive maintenance process are critical tasks. Many diagnosis systems have been proposed to resolve this issue. However, these systems are failing to recognize accurately the type and the severity level of detected faults in real time. In this chapter, a remote automated control approach applied for electrical induction machines has been suggested as an appropriate solution. It combines developed Fast-ESPRIT method, fault classification algorithm, and fuzzy inference system interconnected with vibration sensors, which are located on various wind turbine components. Furthermore, a new fault severity indicator has been formulated and evaluated to avoid false alarms. Study findings with computer simulation in Matlab prove the satisfactory robustness and performance of the proposed technique in fault classification and diagnosis.

Abstract 299: Effect of Start Position and Compression Depth on Mechanical CPR Hemodynamics in Swine

Introduction: Mechanical devices offer the ability to provide consistent fixed-depth chest compressions during CPR. Although compression depth is considered a primary determinant of CPR quality, the influence of other device settings has received less attention. Accordingly, we evaluated the combined effect of compression depth and device start position on CPR hemodynamics in a porcine model of cardiac arrest (CA). Methods: Swine (n=119) were subjected to 7-10 min of CA following electrical induction of ventricular fibrillation. CPR was subsequently performed manually (target peak aortic pressure: 100 mmHg; n=73) or with a mechanical compression system (LUCAS 3.1, Stryker; n=46). Within the mechanical CPR group, animals received 102 compressions/min using either factory default settings (“QuickFit” automated suction cup start position; compression depth: 2.1”; n=13) or custom settings (manual suction cup start position; compression depth: 1.8”; n=33). Aortic pressure (Ao), coronary perfusion pressure (CPP), and regional cerebral oxygen saturation (rSO 2 ; via near infrared spectroscopy) were compared between groups after 1 min of CPR. Results: Mechanical CPR with automated suction cup start position and compression depth of 2.1” resulted in significantly higher peak Ao and CPP than mechanical CPR with manual start position and compression depth of 1.8” ( Table ). Compared with manual CPR, only mechanical CPR with automated start position and compression depth of 2.1” led to a higher CPP. However, cerebral rSO 2 values fell from 61±1 % at baseline to 49±1 % during CA (p<0.01) and did not increase during CPR in any group. Conclusion: Compared with a manual start position and compression depth of 1.8”, use of the LUCAS “QuickFit” feature and compression depth of 2.1” led to a significantly higher CPP during mechanical CPR. Future studies are necessary to determine if differences persist during prolonged CPR with and without concomitant vasopressor administration.

Fault Detection based on MCSA for a 400Hz Asynchronous Motor for Airborne Applications

Future health monitoring concepts in different fields of engineering require reliable fault detection to avoid unscheduled machine downtime. Diagnosis of electrical induction machines for industrial applications is widely discussed in literature. In aviation industry, this topic is still only rarely discussed. A common approach to health monitoring for electrical induction machines is to use Motor Current Signature Analysis (MCSA) based on a Fast Fourier Transform (FFT). Research results on this topic are available for comparatively large motors, where the power supply is typically based on 50Hz alternating current, which is the general power supply frequency for industrial applications. In this paper, transferability to airborne applications, where the power supply is 400Hz, is assessed. Three phase asynchronous motors are used to analyse detectability of different motor faults. The possibility to transfer fault detection results from 50Hz to 400Hz induction machines is the main question answered in this research work. 400Hz power supply frequency requires adjusted motor design, causing increased motor speed compared to 50Hz supply frequency. The motor used for experiments in this work is a 800W motor with 200V phase to phase power supply, powering an avionic fan. The fault cases to be examined are a bearing fault, a rotor unbalance, a stator winding fault, a broken rotor bar and a static air gap eccentricity. These are the most common faults in electrical induction machines which can cause machine downtime. The focus of the research work is the feasibility of the application of MCSA for small scale, high speed motor design, using the Fourier spectra of the current signal. Detectability is given for all but the bearing fault, although rotor unbalance can only be detected in case of severe damage level. Results obtained in the experiments are interpreted withrespect to the motor design. Physical interpretation are given in case the results differ from those found in literature for 50Hz electrical machines.

Central-positive complexes in ECT-induced seizures: Evidence for thalamocortical mechanisms

Electroconvulsive therapy (ECT) relies on the electrical induction of generalized seizures to treat major depressive disorder and other psychiatric illnesses. These planned procedures provide a clinically relevant model system for studying neurophysiologic characteristics of generalized seizures. We recently described novel central-positive complexes (CPCs), which were observed during ECT-induced seizures as generalized, high-amplitude waveforms with maximum positive voltage over the vertex. Here, we performed a systematic characterization of 6,928 CPC ictal waveforms recorded in 11 patients undergoing right unilateral (RUL) ECT. Analyses of high-density 65-electrode EEG recordings during these 50 seizures allowed evaluation of these CPCs across temporal, spatial, and spectral domains. Peak-amplitude CPC scalp topology was consistent across seizures, showing maximal positive polarity over the midline fronto-central region and maximal negative polarity over the suborbital regions. Total duration of CPCs positively correlated with the time required for return of responsiveness after ECT treatment (r = 0.39, p = 0.005). The rate of CPCs showed a frequency decline consistent with an exponential decay (median 0.032 (IQR 0.053) complexes/second). Gamma band (30-80 Hz) oscillations correlated with the peak amplitude of CPCs, which was also reproducible across seizures, with band power declining over time (r = −0.32, p < 10−7). The sources of these peak potentials were localized to the bilateral medial thalamus and cingulate cortical regions. Our findings demonstrated CPC characteristics that were invariant to participant, stimulus charge, time, and agent used to induce general anesthesia during the procedure. Consistent with ictal waveforms of other generalized epilepsy syndromes, CPCs showed topographic distribution over the fronto-central regions, predictable intra-seizure frequency decline, and correlation with gamma-range frequencies. Furthermore, source localization to the medial thalamus was consistent with underlying thalamocortical pathophysiology, as established in generalized epilepsy syndromes. The consistency and reproducibility of CPCs offers a new avenue for studying the dynamics of seizure activity and thalamocortical networks.

Dynamics of Plane Waves in a Semi-Bounded Electro-Magneto-Elastic Medium

The problem of harmonic oscillations in electro-electromagnetic composites is studied. Oscillations can be initiated by the extended load vector, including the horizontal and vertical components of mechanical displacements, and electrical induction distributed on top of the surface. Boundary conditions assume full mechanical coupling for all layers of the structure. Electrical conditions on the surface top can be both electrically open, and electrically shorted. Magnetic conditions are similar to electric ones and describe the continuity of fields in between two mediums, or indicate the isolation of the magnetic field between them. The Green's function of electro–magneto–elastic medium is constructed. Phase velocities are obtained for various geometric proportions and materials.

Thin films of vinylidene fluoride copolymer with tetrafluoroethylene: dynamics of ferroelectric polarization switching

The vinylidene fluoride copolymer with tetrafluoroethylene P(VDF-TFE) is a typical ferroelectric polymer that has not been sufficiently studied so far in comparison with pure polyvinylidene fluoride (PVDF) and its copolymer with trifluoroethylene. The purpose of this work was to reveal the features of forming ferroelectric polarization and its switching in thin films of P(VDF-TFE) under various conditions, such as the level of the applied electric field and the duration of its action within 8 orders of magnitude from 10 μs to 100 s. The sequence of voltage pulses applied during poling and polarization reversal allowed to reveal the characteristics of the polarization switching dynamics. To increase the resolution of the measurements, two complementary methods of recording electrical induction were used. The features of polarization and space charge relaxation over time have been studied by thermally stimulated depolarization method. A new phenomenon of gradual separation of the relaxation processes associated with polarization and space charge was observed. Both components were accompanied by trapped charges that compensated the depolarizing field. Several practical recommendations have been formulated regarding the desirable values of poling parameters and additional processing to increase the ferroelectric polarization stability.