1,102 research outputs found
Compensation of Torque Ripple in High Performance BLDC Motor Drives
Brushless DC motor drives (BLDC) are finding expanded use in high performance applications where torque smoothness is essential. The nature of the square-wave current excitation waveforms in BLDC motor drives permits some important system simplifications compared to sinusoidal permanent magnet AC (PMAC) machines. However, it is the simplicity of the BLDC motor drive that is responsible for causing an additional source of ripple torque commonly known as commutation torque to develop. In this paper, a compensation technique for reducing the commutation torque ripple is proposed. With the experimental results, the proposed method demonstrates the effectiveness for a control system using the BLDC motors that requires high speed and accuracy
Two binary Darboux transformations for the KdV hierarchy with self-consistent sources
Two binary (integral type) Darboux transformations for the KdV hierarchy with
self-consistent sources are proposed. In contrast with the Darboux
transformation for the KdV hierarchy, one of the two binary Darboux
transformations provides non auto-B\"{a}cklund transformation between two n-th
KdV equations with self-consistent sources with different degrees. The formula
for the m-times repeated binary Darboux transformations are presented. This
enables us to construct the N-soliton solution for the KdV hierarchy with
self-consistent sources.Comment: 19 pages, LaTeX, no figures, to be published in Journal of
Mathematical Physic
Quasiparticle spectrum in the vortex state of d-wave superconductors
Quasiparticle spectrum associated with the nodal structure in d-wave
superconductors is of great interest. We study theoretically the quasi-particle
spectrum in a planar magnetic field, where the effect of the magnetic field is
treated in terms of the Doppler shift. We obtain the angular dependent specific
heat in the presence of a planar magnetic field and impurities, both in the
superclean limit (Gamma/Delta << H/H_{c2}<< 1) and in the clean limit (H/H_{c2}
<< Gamma/Delta <<1). Also a similar analysis is used for the thermal
conductivity tensor within the a-b plane. In particular, in contrast to the
earlier works, we find a fourfold symmetry term in \kappa_{\parallel} and
\kappa_{\perp} \sim -H \sin(2\theta) where kappa_{perp} are the diagonal- and
the off-diagonal components of the thermal conductivity tensor and \theta is
the angle between the heat current and the magnetic field.Comment: RevTex, 5 pages, 5 postscript figure
Two-Phase ICM in the Central Region of the Rich Cluster of Galaxies Abell 1795: A Joint Chandra, XMM-Newton, and Suzaku View
Based on a detailed analysis of the high-quality Chandra, XMM-Newton, and
Suzaku data of the X-ray bright cluster of galaxies Abell 1795, we report clear
evidence for a two-phase intracluster medium (ICM) structure, which consists of
a cool (with a temperature T = 2.0-2.2 keV) and a hot (T = 5.0-5.7 keV)
component that coexist and dominate the X-ray emission at least in the central
80 kpc. A third weak emission component (T = 0.8 keV) is also detected within
the innermost 144 kpc and is ascribed to a portion of inter-stellar medium
(ISM) of the cD galaxy. Deprojected spectral analysis reveals flat radial
temperature distributions for both the hot phase and cool phase components.
These results are consistent with the ASCA measurements reported in Xu et al.
(1998), and resemble the previous findings for the Centaurus cluster (e.g.,
Takahashi et al. 2009). By analyzing the emission measure ratio and gas metal
abundance maps created from the Chandra data, we find that the cool phase
component is more metal-enriched than the hot phase one in 50-100 kpc region,
which agrees with that found in M87 (Simionescu et al. 2008). The coexistence
of the cool phase and hot phase ICM cannot be realized by bubble uplifting from
active galactic nuclei (AGN) alone. Instead, the two-phase ICM properties are
better reconciled with a cD corona model (Makishima et al. 2001). (Abridged)Comment: 47 pages, 12 figures, accepted for publication in Ap
Significant correlations between optic nerve head microcirculation and visual field defects and nerve fiber layer loss in glaucoma patients with myopic glaucomatous disk
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Role of Protein Farnesylation in Burn-Induced Metabolic Derangements and Insulin Resistance in Mouse Skeletal Muscle
Objective: Metabolic derangements, including insulin resistance and hyperlactatemia, are a major complication of major trauma (e.g., burn injury) and affect the prognosis of burn patients. Protein farnesylation, a posttranslational lipid modification of cysteine residues, has been emerging as a potential component of inflammatory response in sepsis. However, farnesylation has not yet been studied in major trauma. To study a role of farnesylation in burn-induced metabolic aberration, we examined the effects of farnesyltransferase (FTase) inhibitor, FTI-277, on burn-induced insulin resistance and metabolic alterations in mouse skeletal muscle. Methods: A full thickness burn (30% total body surface area) was produced under anesthesia in male C57BL/6 mice at 8 weeks of age. After the mice were treated with FTI-277 (5 mg/kg/day, IP) or vehicle for 3 days, muscle insulin signaling, metabolic alterations and inflammatory gene expression were evaluated. Results: Burn increased FTase expression and farnesylated proteins in mouse muscle compared with sham-burn at 3 days after burn. Simultaneously, insulin-stimulated phosphorylation of insulin receptor (IR), insulin receptor substrate (IRS)-1, Akt and GSK-3β was decreased. Protein expression of PTP-1B (a negative regulator of IR-IRS-1 signaling), PTEN (a negative regulator of Akt-mediated signaling), protein degradation and lactate release by muscle, and plasma lactate levels were increased by burn. Burn-induced impaired insulin signaling and metabolic dysfunction were associated with increased inflammatory gene expression. These burn-induced alterations were reversed or ameliorated by FTI-277. Conclusions: Our data demonstrate that burn increased FTase expression and protein farnesylation along with insulin resistance, metabolic alterations and inflammatory response in mouse skeletal muscle, all of which were prevented by FTI-277 treatment. These results indicate that increased protein farnesylation plays a pivotal role in burn-induced metabolic dysfunction and inflammatory response. Our study identifies FTase as a novel potential molecular target to reverse or ameliorate metabolic derangements in burn patients
Reproducibility of retinal circulation measurements obtained using laser speckle flowgraphy-NAVI in patients with glaucoma
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