Application of linear magnetic gears for pseudo-direct-drive oceanic wave energy harvesting

Session AZ: Magnetic Machine (Poster Session): AZ-07This paper proposes a linear permanent magnet (PM) machine for direct-drive wave energy harvesting by using a linear magnetic gear. The proposed machine consists of a linear magnetic gear cascaded with a linear PM generator in which the high-speed mover of the linear magnetic gear and the translator of the PM generator artfully shares with the same shaft. In short, the slow reciprocating wave motion is directly captured by the low-speed mover of the gear, and then amplified in speed via the gear to actuate the generator, hence producing higher output voltage. By using finite element analysis, the steady and dynamic performances are analyzed, which confirms that the proposed machine can offer higher power density and higher efficiency than its counterpart. © 2011 IEEE.published_or_final_versionThe IEEE International Magnetic Conference (INTERMAG2011), Taipei, Taiwan, 25-29 April 2011. In IEEE Transactions on Magnetics, 2011, v. 47 n. 10, p. 2624-262

A new efficient permanent-magnet vernier machine for wind power generation

This paper proposes a new outer-rotor permanent-magnet (PM) vernier machine for direct-drive wind power generation, which can offer low-speed operation to directly capture wind power, and enable high-speed rotating field design to maximize the power density. Compared with its mechanical gear counterpart, the proposed machine can eliminate the mechanical wear and tear as well as gear transmission loss, thus improving the generation reliability and efficiency. The key is to newly introduce the flux-modulation poles which can effectively modulate the high-speed rotating field of the armature windings and the low-speed rotating field of the PM outer rotor. By using the time-stepping finite-element method, the proposed machine can be accurately analyzed. Hence, its performances are quantitatively compared with other PM vernier machines, thus verifying its validity. © 2006 IEEE.published_or_final_versio

Analysis of doubly salient memory motors using preisach theory

With the introduction of doubly salient memory (DSM) motors, the flux controllability and hence the speed range of permanent magnet (PM) motors have reached a new height. This paper presents a new method to accurately analyze the DSM motor. The key is to incorporate the general expressions of the Preisach hysteresis model (PHM) of the AlNiCo-PM into the time-stepping finite element method (TS-FEM). Based on the proposed PHM-TS-FEM, both static and transient performances of the DSM motor are successfully simulated. Finally, the validity and accuracy of the proposed method are verified by experimental results. © 2009 IEEE.published_or_final_versio

Comparison of coaxial magnetic gears with different topologies

This paper quantitatively compares two coaxial magnetic gears (CMGs) with different topologies, namely, the CMG installed with radially magnetized permanent magnets (CMGRM) and the CMG installed with Halbach magnetized permanent magnets (CMGHM). By using the 3D finite element method, the end-effect and the performances of both CMGs are investigated. Analysis results show that the CMGHM can offer higher pull-out torque, lower torque ripple and lower iron losses than the CMGRM. Experimental results are also given for verification. © 2009 IEEE.published_or_final_versio

Study of psi(2S) decays to X J/psi

Using J/psi -> mu^+ mu^- decays from a sample of approximately 4 million psi(2S) events collected with the BESI detector, the branching fractions of psi(2S) -> eta J/psi, pi^0 pi^0 J/psi, and anything J/psi normalized to that of psi(2S) -> pi^+ pi^- J/psi are measured. The results are B(psi(2S) -> eta J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.098 \pm 0.005 \pm 0.010, B(psi(2S) -> pi^0 pi^0 J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.570 \pm 0.009 \pm 0.026, and B(psi(2S) -> anything J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 1.867 \pm 0.026 \pm 0.055.Comment: 13 pages, 8 figure

A survey on health-promoting lifestyle among community-dwelling older people with hypertension in Macau

2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Microwave Oscillations of a Nanomagnet Driven by a Spin-Polarized Current

We describe direct electrical measurements of microwave-frequency dynamics in individual nanomagnets that are driven by spin transfer from a DC spin-polarized current. We map out the dynamical stability diagram as a function of current and magnetic field, and we show that spin transfer can produce several different types of magnetic excitations, including small-angle precession, a more complicated large-angle motion, and a high-current state that generates little microwave signal. The large-angle mode can produce a significant emission of microwave energy, as large as 40 times the Johnson-noise background.Comment: 12 pages, 3 figure

A simple, cost-effective but highly efficient system for deriving ventricular cardiomyocytes from human pluripotent stem cells

published_or_final_versio

First observation of psi(2S)-->K_S K_L

The decay psi(2S)-->K_S K_L is observed for the first time using psi(2S) data collected with the Beijing Spectrometer (BESII) at the Beijing Electron Positron Collider (BEPC); the branching ratio is determined to be B(psi(2S)-->K_S K_L) = (5.24\pm 0.47 \pm 0.48)\times 10^{-5}. Compared with J/psi-->K_S K_L, the psi(2S) branching ratio is enhanced relative to the prediction of the perturbative QCD ``12%'' rule. The result, together with the branching ratios of psi(2S) decays to other pseudoscalar meson pairs (\pi^+\pi^- and K^+K^-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.Comment: 5 pages, 4 figures, 2 tables, submitted to Phys. Rev. Let

Influence of interleukin-2 on Ca2+ handling in rat ventricular myocytes

In the present study, we examined the effect of interleukin-2 (IL-2) on cardiomyocyte Ca2+ handling. The effects of steady-state and transient changes in stimulation frequency on the intracellular Ca2+ transient were investigated in isolated ventricular myocytes by spectrofluorometry. In the steady state (0.2 Hz) IL-2 (200 U/ml) decreased the amplitude of Ca2+ transients induced by electrical stimulation and caffeine. At 1.25 mM extracellular Ca2+ concentration ([Ca 2+]o), when the stimulation frequency increased from 0.2 to 1.0 Hz, diastolic Ca2+ level and peak intracellular Ca 2+ concentration ([Ca2+]i), as well as the amplitude of the transient, increased. The positive frequency relationships of the peak and amplitude of [Ca2+]i transients were blunted in the IL-2-treated myocytes. The effect of IL-2 on the electrically induced [Ca2+]i transient was not normalized by increasing [Ca2+]o to 2.5 mM. IL-2 inhibited the frequency relationship of caffeine-induced Ca2+ release. Blockade of sarcoplasmic reticulum (SR) Ca2+-ATPase with thapsigargin resulted in a significant reduction of the amplitude-frequency relationship of the transient similar to that induced by IL-2. The restitutions were not different between control and IL-2 groups at 1.25 mM [Ca2+]o, which was slowed in IL-2-treated myocytes when [Ca2+]o was increased to 2.5 mM. There was no difference in the recirculation fraction (RF) between control and IL-2-treated myocytes at both 1.25 and 2.5 mM [Ca 2+]o. The effects of IL-2 on frequency relationship, restitution, and RF may be due to depressed SR functions and an increased Na+-Ca2+ exchange activity, but not to any change in L-type Ca2+ channels. © 2003 Elsevier Ltd. All rights reserved.postprin