1. On-line foreign object detection using double DD coils in an inductive wireless power transfer systemNataša Prosen, Miro Milanovič, Jure Domajnko, 2022, original scientific article Abstract: This paper proposes an on-line method for foreign object detection in a double DD coil
system. The foreign object is detected by real-time measurement of the mutual inductance between
the transfer pads. Measurement of the mutual inductance between coils can be performed at the
start, during initialisation, or during the wireless power transfer. The coils in the double DD coil
structure can be used separately; one coil can be used for power transfer and the other can be used
for the mutual inductance measurement. The mutual inductance measurement is based on the
voltage measurement across the open circuit receiver coil. The measured value of mutual inductance
between the transmitter and the receiver pad can be used in a control algorithm and in a foreign
object detection algorithm. Additionally, a 2DDq coil structure can be used as a replacement for the
double DD coil structure, which increases the power transfer density. The DD coils in the double DD
coil structure can also be driven using two phase-shifted voltages, which enables better location and
detection of foreign objects. The method also helps to differentiate the mutual inductance change due
to the distance change from the mutual inductance change due to the presence of a foreign object.
Keywords: WPT, double DD coil structure, mutual inductance measurement, coupling coefficient measurement, FOD, on-line measurement
Published in DKUM: 01.04.2025; Views: 0; Downloads: 2
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2. 3D platform for coupling coefficient evaluation of an inductive power transfer systemsJure Domajnko, Miro Milanovič, Nataša Prosen, 2022, original scientific article Abstract: This paper presents a custom-made, computer-connected, and controlled 3D platform that
enables the evaluation of the coupling coefficient between the transmitter and receiver coil parts of an
inductive wireless power transfer (IPT) system. The platform includes a computer application, a 3D
positioning mechanism, and an inductance measurement circuit. The positioning mechanism moves
the coils to the point in 3D space, and the inductance circuit measures the mutual inductance between
the transmitter and the receiver coil. The measured value can be used to calculate the coupling
coefficient between the transmitter and the receiver coil. The data are sent to the computer for further
visualisation. The transmitter and the receiver coil can be evaluated by measuring the coupling
coefficient between them in multiple points in space. Measurements performed with the platform
can be used in the design and evaluation phases of inductive wireless power transfer systems and to
extrapolate the polynomial function of the coupling coefficient in relation to the distance between
coils or their misalignment.
Keywords: coupling coefficient, inductance measurement, IPT coil design
Published in DKUM: 01.04.2025; Views: 0; Downloads: 3
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4. The role of cAMP in beta cell stimulus-secretion and intercellular couplingAndraž Stožer, Eva Paradiž, Viljem Pohorec, Jurij Dolenšek, Lidija Križančić Bombek, Marko Gosak, Maša Skelin, 2021, review article Abstract: Pancreatic beta cells secrete insulin in response to stimulation with glucose and other nutrients, and impaired insulin secretion plays a central role in development of diabetes mellitus. Pharmacological management of diabetes includes various antidiabetic drugs, including incretins. The incretin hormones, glucagon-like peptide-1 and gastric inhibitory polypeptide, potentiate glucose-stimulated insulin secretion by binding to G protein-coupled receptors, resulting in stimulation of adenylate cyclase and production of the secondary messenger cAMP, which exerts its intracellular effects through activation of protein kinase A or the guanine nucleotide exchange protein 2A. The molecular mechanisms behind these two downstream signaling arms are still not fully elucidated and involve many steps in the stimulus-secretion coupling cascade, ranging from the proximal regulation of ion channel activity to the central Ca2+ signal and the most distal exocytosis. In addition to modifying intracellular coupling, the effect of cAMP on insulin secretion could also be at least partly explained by the impact on intercellular coupling. In this review, we systematically describe the possible roles of cAMP at these intra- and inter-cellular signaling nodes, keeping in mind the relevance for the whole organism and translation to humans.
Keywords: cAMP, beta cells, stimulus-secretion coupling, intercellular coupling, PKA, Epac2A
Published in DKUM: 16.10.2024; Views: 0; Downloads: 6
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5. Optimization of a circular planar spiral wireless power transfer coil using a genetic algorithmNataša Prosen, Jure Domajnko, 2024, original scientific article Abstract: Circular planar spiral coils are the most important parts of wireless power transfer systems. This paper presents the optimization of wireless power transfer coils used for wireless power transfer, which is a problem when designing wireless power transfer systems. A single transmitter coil transfers power to a single receiving side. The performance of the wireless power transfer system depends greatly on the size and shape of the wireless power transfer system. Therefore, the optimization of the coils is of the utmost importance. The main optimization parameter was the coupling coefficient between the transmitter and the receiver coil in the horizontally aligned and misaligned position. A genetic evolutionary algorithm was used to optimize the coil, according to the developed cost function. The algorithm was implemented using the MATLAB programming language. The constraints regarding the design of the coils are also presented for the problem to be analyzed correctly. The results obtained using the genetic algorithm were first verified using FEM simulations. The optimized coils were later fabricated and measured to confirm the theory.
Keywords: wireless power transfer, coil optimization, genetic algorithm, coupling coefficient measurement
Published in DKUM: 14.08.2024; Views: 77; Downloads: 9
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6. Swarmalators under competitive time-varying phase interactionsGourab Kumar Sar, Sayantan Nag Chowdhury, Matjaž Perc, Dibakar Ghosh, 2022, original scientific article Abstract: Swarmalators are entities with the simultaneous presence of swarming and synchronization that reveal emergent collective behavior due to the fascinating bidirectional interplay between phase and spatial dynamics. Although different coupling topologies have already been considered, here we introduce time-varying competitive phase interaction among swarmalators where the underlying connectivity for attractive and repulsive coupling varies depending on the vision (sensing) radius. Apart from investigating some fundamental properties like conservation of center of position and collision avoidance, we also scrutinize the cases of extreme limits of vision radius. The concurrence of attractive–repulsive competitive phase coupling allows the exploration of diverse asymptotic states, like static π, and mixed phase wave states, and we explore the feasible routes of those states through a detailed numerical analysis. In sole presence of attractive local coupling, we reveal the occurrence of static cluster synchronization where the number of clusters depends crucially on the initial distribution of positions and phases of each swarmalator. In addition, we analytically calculate the sufficient condition for the emergence of the static synchronization state. We further report the appearance of the static ring phase wave state and evaluate its radius theoretically. Finally, we validate our findings using Stuart–Landau oscillators to describe the phase dynamics of swarmalators subject to attractive local coupling.
Keywords: swarmalators, time-varying couplings, synchronization, competitive phase coupling
Published in DKUM: 16.07.2024; Views: 87; Downloads: 12
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7. Effects of atrial fibrillation on the human ventricleSteffen Pabel, Maria Knierim, Thea Stehle, Felix Alebrand, Michael Paulus, Marcel Sieme, Melissa Herwig, Friedrich Barsch, Thomas Körtl, Arnold Pöppl, Simon Sedej, 2022, original scientific article Abstract: Rationale: Atrial fibrillation (AF) and heart failure often coexist, but their interaction is poorly understood. Clinical data indicate that the arrhythmic component of AF may contribute to left ventricular (LV) dysfunction.
Objective: This study investigates the effects and molecular mechanisms of AF on the human LV.
Methods and results: Ventricular myocardium from patients with aortic stenosis and preserved LV function with sinus rhythm or rate-controlled AF was studied. LV myocardium from patients with sinus rhythm and patients with AF showed no differences in fibrosis. In functional studies, systolic Ca2+ transient amplitude of LV cardiomyocytes was reduced in patients with AF, while diastolic Ca2+ levels and Ca2+ transient kinetics were not statistically different. These results were confirmed in LV cardiomyocytes from nonfailing donors with sinus rhythm or AF. Moreover, normofrequent AF was simulated in vitro using arrhythmic or rhythmic pacing (both at 60 bpm). After 24 hours of AF-simulation, human LV cardiomyocytes from nonfailing donors showed an impaired Ca2+ transient amplitude. For a standardized investigation of AF-simulation, human iPSC-cardiomyocytes were tested. Seven days of AF-simulation caused reduced systolic Ca2+ transient amplitude and sarcoplasmic reticulum Ca2+ load likely because of an increased diastolic sarcoplasmic reticulum Ca2+ leak. Moreover, cytosolic Na+ concentration was elevated and action potential duration was prolonged after AF-simulation. We detected an increased late Na+ current as a potential trigger for the detrimentally altered Ca2+/Na+-interplay. Mechanistically, reactive oxygen species were higher in the LV of patients with AF. CaMKII (Ca2+/calmodulin-dependent protein kinase IIδc) was found to be more oxidized at Met281/282 in the LV of patients with AF leading to an increased CaMKII activity and consequent increased RyR2 phosphorylation. CaMKII inhibition and ROS scavenging ameliorated impaired systolic Ca2+ handling after AF-simulation.
Conclusions: AF causes distinct functional and molecular remodeling of the human LV. This translational study provides the first mechanistic characterization and the potential negative impact of AF in the absence of tachycardia on the human ventricle.
Keywords: atrial fibrillation, calcium-calmodulin-dependent protein kinase type 2, excitation contraction coupling, heart failure, oxidative stress
Published in DKUM: 28.06.2024; Views: 115; Downloads: 9
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8. A point particle source model for conjugate heat and mass transfer in dispersed two-phase flows by BEM based methodsTimi Gomboc, Jurij Iljaž, Jure Ravnik, Matjaž Hriberšek, 2023, original scientific article Keywords: boundary-domain integral method, dispersed two-phase flow, two-way coupling, spherical porous particles, drying
Published in DKUM: 28.03.2024; Views: 217; Downloads: 21
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9. Calorimetric insight into coupling between functionalized primary alkyl halideand vinylic organocuprate reagent : experimental determination of reaction enthalpies in the synthesis of (R)-ethyl 3-(tert-butyldimethylsilyloxy)hex-5-enoate - a key lactonized statinside chain precursorZdenko Časar, Marko Tramšek, Andreja Goršek, 2010, original scientific article Abstract: The first calorimetric study of coupling between organocuprate, derived from Grignard reagent (vinyl magnesium chloride), and primary alkyl halide (e.g. (S)-ethyl 3-(tert-butyldimethylsilyloxy)-4-iodobutanoate) has been conducted. This transformation is paramountly important for efficient preparation of (R)-ethyl 3-(tert-butyldimethylsilyloxy)hex-5-enoate – a key lactonized statin side chain precursor. The results obtained give thorough calorimetric insight into this complex low-temperature synthesis as well as a new understanding of the suggested reductive elimination of the final intermediates in the coupling reaction. Namely, the surprising unexpected spontaneous three-step exothermal event has been observed during controlled progressive heating of the mixture of the final intermediates to the room temperature. This phenomenon confirms that coupling between functionalized primary alkyl halide and vinylic organocuprate reagent is not a simple $S_N2$ substitution reaction. The presented study provides among others the first reported values of reaction enthalpies and corresponding adiabatic temperature rises of reaction mixture for all exothermic events that occurred in the (R)-ethyl 3-(tert-butyldimethylsilyloxy)hex-5-enoate synthesis. The obtained results ensure consequential thermal process safety knowledge which can be incorporated into safe process scale-up as well as design of reactor system with sufficient cooling capacity for industrial production of (R)-ethyl 3-(tert-butyldimethylsilyloxy)hex-5-enoate. Moreover, the results provide a basic guidance for other organocuprate coupling reaction systems.
Keywords: Grignard reagents, organocuprates, coupling reaction, reaction calorimetry, statins
Published in DKUM: 17.08.2017; Views: 1134; Downloads: 109
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10. Gap junctions and epileptic seizures - two sides of the same coin?Vladislav Volman, Matjaž Perc, Maxim Bazhenov, 2011, original scientific article Abstract: Electrical synapses (gap junctions) play a pivotal role in the synchronization of neuronal ensembles which also makes them likely agonists of pathological brain activity. Although large body of experimental data and theoretical considerations indicate that coupling neurons by electrical synapses promotes synchronous activity (and thus is potentially epileptogenic), some recent evidence questions the hypothesis of gap junctions being among purely epileptogenic factors. In particular, an expression of inter-neuronal gap junctions is often found to be higher after the experimentally induced seizures than before. Here we used a computational modeling approach to address the role of neuronal gap junctions in shaping the stability of a network to perturbations that are often associated with the onset of epileptic seizures. We show that under some circumstances, the addition of gap junctions can increase the dynamical stability of a network and thus suppress the collective electrical activity associated with seizures. This implies that the experimentally observed post-seizure additions of gap junctions could serve to prevent further escalations, suggesting furthermore that they are a consequence of an adaptive response of the neuronal network to the pathological activity. However, if the seizures are strong and persistent, our model predicts the existence of a critical tipping point after which additional gap junctions no longer suppress but strongly facilitate the escalation of epileptic seizures. Our results thus reveal a complex role of electrical coupling in relation to epileptiform events. Which dynamic scenario (seizure suppression or seizure escalation) is ultimately adopted by the network depends critically on the strength and duration of seizures, in turn emphasizing the importance of temporal and causal aspects when linking gap junctions with epilepsy.
Keywords: epilepsy, nonlinear dynamics, electrical synapses, coupling, synchronization
Published in DKUM: 19.06.2017; Views: 1119; Downloads: 419
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