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Recently, an omnidirectional wireless power transfer (WPT) has attracted attention as a solution to the limitations of free-positioning and mobility of conventional WPT. However, the efficiency of the omnidirectional WPT is reduced due to the low mutual inductance relative to the transmitter size. Therefore, this article proposed an optimal magnetic structure to improve efficiency without increasing the size of the transmitter. Four magnetic structure candidates (spherical, cubical, crossed bar, three-orthogonal plane core) are presented and their performances are compared using finite element analysis software. A Pareto optimal set is selected using a multiobjective optimization design, and the optimal magnetic structure is determined considering the weight of the objective variable and the Tchebycheff distance. The optimal magnetic structure and omnidirectional WPT prototype are built for performance verification. The experimental results are consistent with the simulation results and demonstrate that the optimal magnetic structure improves the efficiency in the three-dimensional space. When the power transmission distance is 150 mm, the system efficiency is improved up to 18.6%. [ABSTRACT FROM AUTHOR]

Virtually all biomedical applications of positron emission tomography (PET) use images to represent the distribution of a radiotracer. However, PET is increasingly used in cell tracking applications, for which the “imaging” paradigm may not be optimal. Here, we investigate an alternative approach, which consists in reconstructing the time-varying position of individual radiolabeled cells directly from PET measurements. As a proof of concept, we formulate a new algorithm for reconstructing the trajectory of one single moving cell directly from list-mode PET data. We model the trajectory as a 3-D B-spline function of the temporal variable and use nonlinear optimization to minimize the mean-square distance between the trajectory and the recorded list-mode coincidence events. Using Monte Carlo simulations (GATE), we show that this new algorithm can track a single source moving within a small-animal PET system with <3 mm accuracy provided that the activity of the cell [Bq] is greater than four times its velocity [mm/s]. The algorithm outperforms conventional ML-EM as well as the “minimum distance” method used for positron emission particle tracking (PEPT). The new method was also successfully validated using experimentally acquired PET data. In conclusion, we demonstrated the feasibility of a new method for tracking a single moving cell directly from PET list-mode data, at the whole-body level, for physiologically relevant activities and velocities. [ABSTRACT FROM PUBLISHER]

With much effort devoted by many research groups, the performance of 2nd generation (2G) superconducting wires, also called coated conductors (CC), was drastically improved, leading to many meaningful and impressive demonstrations of electric power devices. Now that the performances such as critical current, in-field characteristics, and mechanical strengths became sufficient to the application, the attention has moved to how we can produce long 2G wires with high uniformity. Many in-line inspection tools are tested and introduced to address these challenges. In this paper, we describe two methods that we adopted for in-line monitoring and feedback control of layer deposition. One is for texture control of ion beam assisted deposition (IBAD) of an MgO layer through reflection high-energy electron diffraction (RHEED) pattern monitoring and analysis. The other is for composition control of a superconducting layer through surface color observation and control of metal source evaporation rates. By applying the above two methods, we achieved in-plane texture of about 4.8^ \circ in the MgO layer, as measured by FWHM of phi-scan of (220) peak, and the critical current of 750 A/12 mm width in the GdBCO layer along the length of more than 650 m, with excellent uniformity. [ABSTRACT FROM PUBLISHER]

In this paper, a new topology is proposed that can significantly reduce the converter rated power and increase the efficiency of total photovoltaic (PV) system. Since the output voltage of PV module has very wide operating range, in general, the dc/dc converter is used to produce constant high-dc-link voltage for dc/ac inverter. According to the analysis of the proposed topology, only 20% of total PV system power is processed by the dc/dc power conversion stage. The dc/dc power conversion stage used in proposed topology has flat efficiency curve throughout all load range and very high efficiency characteristics. In the proposed topology, because the converter efficiency curve is almost flat throughout all load range, the total system efficiency at light load is dramatically improved. The proposed topology is implemented for 250-kW power conditioning system. This system has only three dc/dc power conversion stage with 24-kW rated power. It is only one-third of total system power. The experimental results show that the proposed topology has good performance. [ABSTRACT FROM AUTHOR]