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During the typical constant current (CC) charging process, the supercapacitor has a pretty wide-range load variation. However, an inductive power transfer (IPT) converter can only maintain high efficiency within a certain load range around its optimum load point. Once the supercapacitor load resistance is far away from the optimum point, which usually happens in low charging power levels, i.e., the smaller load resistances, the IPT converter will suffer from the dramatic efficiency degradation and thus a step-up load transformation is required throughout the whole charging process. In this paper, a novel current-controlled semi-active rectifier (CCSAR) based IPT converter is proposed to fulfill this requirement. The characteristic of step-up load transformation is firstly identified and implemented by controlling the conduction angle of the CCSAR to enhance the efficiency in the charging process. The desired charging CC is then regulated by tuning the operating frequency of the IPT inverter. To coordinate these two objectives, a bivariate control is adopted here to achieve fast, direct and precise current output with enhanced efficiency performance over the whole load range during the CC charging process. Finally, experiment results validate the theoretical analysis well.

A high-performance capacitive power transfer (CPT) system is expected to achieve the load-independent constant output, near-zero reactive power, and soft switching of power switches simultaneously, resulting in a reduced power stage, simple control circuitry, and minimum component ratings. However, a well-compensated CPT system still suffers very high voltage stresses among not only the main coupled plates but also the leakage coupled plates due to the small coupling and edge emission, which increase the risk of air breakdown and deteriorate the electromagnetic interference (EMI) issue. To solve this problem, the voltage stresses among such coupler plates should be predesigned at an acceptable level. This paper systematically analyzes characteristics of a double-sided LCLC compensated CPT converter, which is proved to have enough design freedom providing predesigned voltage stresses for two kinds of coupled plates. Also, three operating frequencies with load-independent constant current (CC) output and input zerophase angle (ZPA) are found. Without reactive power in the circuit, a parameter design method is proposed for the doublesided LCLC compensated CPT converter at each frequency to satisfy the desired CC output and the predesigned voltage limitations. In this way, the breakdown and EMI issues can be well mitigated by the intended design and this method can also be extended to other CPT circuits. Finally, a CPT prototype is built to verify the theoretical analysis with the predesigned voltage stresses among the coupler plates.

Kinetics of a reaction network that follows mass-action rate laws can be described with a system of ordinary differential equations (ODEs) with polynomial right-hand side. However, it is challenging to derive such kinetic differential equations from transient kinetic data without knowing the reaction network, especially when the data are incomplete due to experimental limitations. We introduce a program, PolyODENet, toward this goal. Based on the machine-learning method Neural ODE, PolyODENet defines a generative model and predicts concentrations at arbitrary time. As such, it is possible to include unmeasurable intermediate species in the kinetic equations. Importantly, we have implemented various measures to apply physical constraints and chemical knowledge in the training to regularize the solution space. Using simple catalytic reaction models, we demonstrate that PolyODENet can predict reaction profiles of unknown species and doing so even reveal hidden parts of reaction mechanisms.

Multiloop constant on-time (COT) controlled buck converter uses two weight resistors for sensing inductor current and detecting output voltage in its inner loop. When an output capacitor with a small equivalent series resistance (ESR) is employed, the converter will suffer the risk of instability due to different weight settings of inductor current and output voltage using a proportional–integral (PI) compensation gain in the outer voltage loop. However, no attention has been paid for their stability effects, which are important for designing the inner loop and outer voltage loop. To address these issues, a piecewise linear model is established for multiloop COT-controlled buck converter. Circuit parameter-related bifurcation behaviors and control weight-related dynamical distributions are explored to demonstrate these stability effects. Furthermore, by deriving an approximate discrete model, a control weight-related stability criterion is expressed explicitly, from which stability boundaries for dividing the normally stable and abnormally unstable operation parameter regions are thereby yielded. Besides, control weight-related transient performances under different circuit parameter settings are analyzed. Finally, PSIM circuit simulations and hardware circuit experiments verify the theoretical analysis well.

A constant current (CC) output followed by a constant voltage (CV) threshold is usually needed for an inductive power transfer (IPT) charger to comply with the battery charging profile. This letter proposes a novel clamp coil assisted IPT battery charger that features inherent, passive, automatic, and smooth CC-to-CV transition. Since the CC-to-CV transition eliminates the necessity of state-of-charge detection, wireless feedback communication, and active control, the proposed IPT charger is rugged and reliable. The inherent CC-to-CV transition capability also tackles the open-circuit risk during a CC charging process. As minimalist design is achieved in the secondary, the proposed IPT charger is suitable for wireless onboard charging applications. Near-unity power factor design is also considered to minimize the voltage–ampere rating and permits soft switching. Experiment results validate the inherent CC-to-CV transition capability.

In situ synchrotron X-ray absorption near-edge structure characterization of thin-film titania growth by atomic layer deposition (ALD) over ZnO nanowires reveals persistent low-coordinated Ti motif...

Inductive power transfer (IPT) systems have many unique benefits compared to conventional plugged-in systems. The coupling pads in IPT systems are inevitably misaligned in many practical applications, thus leading to variations of the transferred power and efficiency that necessitate the use of complicated control for output regulation. A common solution is to use two IPT converters with opposite trends of output to pad misalignment, so that the total output voltage or current could be kept near constant for large coupling variations. However, methods for deriving effective configurations for such hybrid IPT converters and their achievable tolerance to the misalignment are still missing. This article constructs a family of hybrid IPT topologies, including input-parallel–output-parallel, input-parallel–output-series, input-series–output-parallel (ISOP), and input-series–output-series for delivering a constant current (CC) or a constant voltage (CV). Design principles and characteristics for all the hybrid systems with near load-independent output and high tolerance to pad misalignment are derived and discussed in detail. Based on this family of configurations, this article also combines some existing IPT topologies and derives multiple hybrid converters for CC or CV output by using a simple duty cycle control. Finally, a 3.5-kW hybrid IPT prototype converter based on the ISOP structure is built to verify the theoretical analysis.

Empirical data reveal that fair value measurement (FVM) is mostly used for the measurement of financial assets and liabilities and slightly used for the measurement of investment property. Both the...

Translation in eukaryotic cells occurs predominantly through a 7-methylguanosine (m7G) cap-dependent mechanism. m7G cap interactions with eukaryotic initiation factor 4E (eIF4E) facilitates 43S recruitment to the mRNA 5’ end and enhances the translation efficiency of mRNA. However, it remains poorly understood how m7G cap-eIF4E interactions affect polysome formation kinetics. Here, we examine the role of the m7G cap in polysome formation by utilizing a single-molecule approach to track individual ribosomes during active translation. Translation was monitored in wheat germ extract with capped and uncapped synthetic mRNAs and in HeLa extract with purified human eIF4E titration. The presence of the m7G cap and the supplementation of eIF4E to eIF4E-deficient extract enhanced the kinetics of the first initiation event of polysomes. Subsequent to the first initiation event, efficient polysome-forming initiation events occurred independent of mRNA m7G capping status and eIF4E concentration. Our results indicate that m7G cap-eIF4E interactions in wheat germ and HeLa extracts promote polysome formation by enhancing first-round initiation kinetics. The dynamics of individual translation events on polysomal mRNAs suggest that first-round initiation events activate mRNAs for efficient subsequent rounds of polysome-forming initiation.