A general method for designing the transformer of flyback converters based on nonlinear FEA of electromagnetic field coupled with external circuit

This paper presents a general method for designing the transformer of flyback switching AC-DC converters based on nonlinear finite element analysis (FEA) of electromagnetic field coupled with external circuit. For that, the variation patterns of the PWM duty ratio and the current flowing through the windings of transformer versus the input voltage are introduced first, and then several important principles for the design of the transformer are given by using analytical method. As the magnetic saturation and control delay possess heavy influence on the safety of the operation, a MATLAB/Simulink based simulation model, in which both the nonlinear differential inductance and the control delay are included, is built to predict the converter transient performance. The nonlinear differential inductance is calculated by a general program of nonlinear 2-D FEA in Matlab/Simulink surrounding. By running the model, the performances of the converter with different loads and input voltages are obtained. Simulation results are in good agreement with theoretical analysis

A unified hybrid model with two level networks for peak current mode controlled buck-boost converters operating in DCM and CCM

Theis paper presents a unified hybrid model with two level networks for peak current mode controlled buck-boost converters operating in continuous conduction mode (CCM) and discontinuous conduction mode (DCM). It is a network model with two levels in which both a detailed switching model and a small signal average model are included correspondingly. The nonlinearity of some electronic components and the parasitical effects of circuit elements are considered. The nonlinear inductance is calculated by finite element analysis (FEA). The dynamical performance of the buck-boost converter can be obtained from the detailed switching model in the first level network, and then the frequency domain performance can be obtained from the average model in the second level network. As an automatic mechanism of exchanging data between two models is proposed, all the performances can be obtained automatically. By implementing the proposed model in Simulink surrounding, both the large signal transient performance and the frequency domain behavior of converters are obtained efficiently

Vortex charges in high-temperature superconductors

The vortex charge in high-temperature superconductors was investigated. It was found that the vortex charge was negative when a sufficient strength of antiferromagnetic (AF) order was induced inside the vortex core. The vortex charge at optimal doping was studied as a function of magnetic field. The results showed that the AF order was absent inside the vortex core for small Coulomb repulsion.published_or_final_versio

Recent changes of water discharge and sediment load in the Yellow River basin, China

The Yellow River basin contributes approximately 6% of the sediment load from all river systems globally, and the annual runoff directly supports 12% of the Chinese population. As a result, describing and understanding recent variations of water discharge and sediment load under global change scenarios are of considerable importance. The present study considers the annual hydrologic series of the water discharge and sediment load of the Yellow River basin obtained from 15 gauging stations (10 mainstream, 5 tributaries). The Mann-Kendall test method was adopted to detect both gradual and abrupt change of hydrological series since the 1950s. With the exception of the area draining to the Upper Tangnaihai station, results indicate that both water discharge and sediment load have decreased significantly (p<0.05). The declining trend is greater with distance downstream, and drainage area has a significant positive effect on the rate of decline. It is suggested that the abrupt change of the water discharge from the late 1980s to the early 1990s arose from human extraction, and that the abrupt change in sediment load was linked to disturbance from reservoir construction.Geography, PhysicalGeosciences, MultidisciplinarySCI(E)43ARTICLE4541-5613

Improved Charge-Trapping Properties of TiON/HfON Dual Charge Storage Layer by Tapered Band Structure

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Improved Memory Characteristics by NH3-Nitrided GdO as Charge Storage Layer for Nonvolatile Memory Applications

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Improved performance by using TaON/SiO2 as dual tunnel layer in Charge-Trapping nonvolatile memory

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Micromagnetic simulations of current-induced magnetization switching in Co/Cu/Co nanopillars

Author name used in this publication: S. Q. Shi2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Current-induced magnetization dynamics in Co/Cu/Co nanopillars

Author name used in this publication: S. Q. Shi2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Wavelength-multiplexed duplex transceiver based on III-V/Si hybrid integration for off-chip and on-chip optical interconnects

A six-channel wavelength-division-multiplexed optical transceiver with a compact footprint of 1.5 x 0.65 mm(2) for off-chip and on-chip interconnects is demonstrated on a single silicon-on-insulator chip. An arrayed waveguide grating is used as the (de)multiplexer, and III-V electroabsorption sections fabricated by hybrid integration technology are used as both modulators and detectors, which also enable duplex links. The 30-Gb/s capacity for each of the six wavelength channels for the off-chip transceiver is demonstrated. For the on-chip interconnect, an electrical-to-electrical 3-dB bandwidth of 13 GHz and a data rate of 30 Gb/s per wavelength are achieved