Variational Formulations for Electromagnetic Field and Charged-Particle Stream Configurations and Their Linearization

Two variational formulations for electromagnetic field and charged-particle stream configurations, in which both field and particles are described by the field-like variables suited for the problems of electrodynamics, are presented. One of them is directly obtained through slight modifications of Sturrock's original procedure but has a complicated form. The other is obtained through linearization of the preceding one and has a compact form. Both formulations lend themselves to straightforward derivation of the well-known energy-momentum tensor and/or its conservation law. Specifically the latter one is of academic interest because of its compact form. Moreover, as a proof of its practical usefulness the variational principle under the small-amplitude approximation is derived from it, which is known to provide a basis for the study of certain types of instability in plasmas. It is, however, hoped that it will find main applications in the electrodynamics problems concerned with large-amplitude behavior

Proposal on Model Based Current Overshoot Suppression of Receiver Side Coil in Drone Wireless Power Transfer System

This paper proposes a model-based control method in the wireless power transfer (WPT) system by operating a semi-bridgeless active rectifier (SBAR) to suppress the secondary coil current overshoot. By damping the current overshoot, it is possible to reduce the rectifier's rated current and decrease the rectifier's size, which is beneficial for the lightweight-oriented system such as drones. In the control method, an inverse of the plant model is used to calculate the reference input to the system. The current overshoot is reduced by operating the SBAR under the duty ratio calculated from the model. To confirm the performance of the proposed method, the simulation and the experiment using the WPT prototype are conducted. The experimental results show that the proposed method can suppress the secondary coil current overshoot. The results suggest it is possible to realize the lighter secondary system by applying the proposed method.Comment: This paper was presented at IEEE 2022 Wireless Power Week (WPW

Fatigue Limit Reliability Analysis for Notched Material with Some Kinds of Dense Inhomogeneities Using Fracture Mechanics

This study proposes a quantitative method for predicting fatigue limit reliability of a notched metal containing inhomogeneities. Since the fatigue fracture origin of the notched metal cannot be determined in advance because of stress nonuniformity, randomly distributed particles, and scatter of a matrix, it is difficult to predict the fatigue limit. The present method utilizes a stress-strength model incorporating the “statistical hardness characteristics of a matrix under small indentation loads” and the “statistical hardness characteristics required for non-propagation of fatigue cracks from microstructural defects”. The notch root is subdivided into small elements to eliminate the stress nonuniformity. The fatigue limit reliability is predicted by unifying the survival rates of the elements obtained by the stress-strength model according to the weakest link model. The method is applied to notched specimens of aluminum cast alloy JIS AC4B-T6 containing eutectic Si, Fe compounds and porosity. The fatigue strength reliability at 107 cycles, which corresponds to the fatigue limit reliability, is predicted. The fatigue limits of notch root radius ρ = 2, 1, 0.3, and 0.1 mm are obtained by rotating-bending fatigue tests. It is shown that the fatigue limits predicted by the present method are in good agreement with the experimental ones

The dynamic right-to-left translocation of Cerl2 is involved in the regulation and termination of nodal activity in the mouse node

The determination of left-right body asymmetry in mouse embryos depends on the interplay of molecules In a highly sensitive structure, the node. Here, we show that the localization of Cerl2 protein does not correlate to its mRNA expression pattern, from 3-somite stage onwards. Instead, Cerl2 protein displays a nodal flow-dependent dynamic behavior that controls the activity of Nodal in the node, and the transmission of the laterality information to the left lateral plate mesoderm (LPM). Our results indicate that Cerl2 initially localizes and prevents the activation of Nodal genetic circuitry on the right side of the embryo, and later its right-to-left translocation shutdowns Nodal activity in the node. The consequent prolonged Nodal activity in the node by the absence of Cerl2 affects local Nodal expression and prolongs its expression in the LPM. Simultaneous genetic removal of both Nodal node inhibitors, Cerl2 and Lefty1, sustains even longer and bilateral his LPM expression.F.C.T.; IBB/CBME, LAinfo:eu-repo/semantics/publishedVersio