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Operation Characteristics (operation + characteristic)
Selected AbstractsA method to determine direct- and quadrature-axis inductances of permanent magnet synchronous motorsELECTRICAL ENGINEERING IN JAPAN, Issue 3 2010Shu Yamamoto Abstract The equivalent circuit constants of permanent magnet synchronous motors are needed in the calculation of operation characteristics, construction of a control system, etc. These constants can be computed from the data on structural form and materials. However, measurements are necessary to obtain highly precise values. Methods for measurement of the d- and q-axis inductances can be roughly divided into rotational and standstill methods. The standstill methods have the advantage that they are easy to carry out. However, it is difficult to consider magnetic saturation and distortion of the change in the armature winding inductance. The accuracy of the standstill method can be improved if these effects can be readily taken into account. This paper describes a standstill method for measuring accurate d- and q-axis synchronous inductances of permanent magnet synchronous motors. By utilizing the fact that the EMF interference terms in the motor voltage equation considering the distortion of the inductance change are equal to zero when the rotor is in a specific position, the proposed method determines the inductances considering both magnetic saturation and inductance distortion effects from simple off-line standstill testing. In addition, this method is capable of taking cross-magnetic saturation into account when used with the necessary testing equipment. The proposed method was implemented on a 0.4-kW interior permanent magnet synchronous motor with concentrated stator winding. The validity of the proposed method was demonstrated by comparing the measured and calculated results of the no-load and on-load characteristics. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 41,50, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20969 [source] Direct-power-control-based matrix converter and its operation characteristicsELECTRICAL ENGINEERING IN JAPAN, Issue 2 2010Toshihiko Noguchi Abstract This paper proposes a novel control strategy for a matrix converter, which features direct instantaneous active- and reactive-power control of the converter. The theoretical aspects of the proposed control are discussed, and computer simulation results are presented to confirm the basic controllability of the technique. In addition, several operational characteristics were examined through experimental tests, using a 1.5-kW prototype. The maximum efficiency and the total input power factor of the prototype with a 30-Hz output frequency were 95.4% and 99.9% at 1.5-kW load, respectively. The total harmonic distortion at the rated load was 5.9%. These results demonstrate the feasibility and effectiveness of the proposed strategy. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(2): 53,59, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20886 [source] Wavelength-dispersive spectrometer for X-ray microfluorescence analysis at the X-ray microscopy beamline ID21 (ESRF)JOURNAL OF SYNCHROTRON RADIATION, Issue 3 2010J. Szlachetko The development of a wavelength-dispersive spectrometer for microfluorescence analysis at the X-ray Microscopy ID21 beamline of the European Synchrotron Radiation Facility (ESRF) is reported. The spectrometer is based on a polycapillary optic for X-ray fluorescence collection and is operated in a flat-crystal geometry. The design considerations as well as operation characteristics of the spectrometer are presented. The achieved performances, in particular the energy resolution, are compared with the results of Monte Carlo simulations. Further improvement in the energy resolution, down to ,eV range, by employing a double-crystal geometry is examined. Finally, examples of applications requiring both spatial and spectral resolutions are presented. [source] Phonation threshold flow measurements in normal and pathological phonationTHE LARYNGOSCOPE, Issue 4 2009Peiyun Zhuang MD Abstract Objectives/Hypothesis: Phonation threshold flow (PTF) may provide a tool to assess laryngeal function and could differentiate between normal and pathological voices. Both polyps and nodules contribute to an increased PTF by creating an incomplete glottal closure and increased vocal fold mass and thickness. Study Design: Prospective study. Methods: The Kay Elemetrics Phonatory Aerodynamic System (PAS) (Kay Elemetrics Corp., Lincoln Park, NJ) was used to collect mean flow rate (MFR) and PTF measurements from 40 normal subjects, 21 patients with vocal fold nodules, and 23 patients with vocal fold polyps. Gender-based differences were assessed using a t test. The effect of vocal pathology on PTF and MFR was determined with an ANOVA. Diagnostic potential was evaluated using a receiver operation characteristics (ROC) analysis. Results: Both PTF (P = .047) and MFR (P = .008) were significantly affected by gender. Using a two-way ANOVA and correcting for gender differences, the influence of pathology on PTF was determined to be significant (P < .001). Post hoc tests found a significant difference between normal and polyp subjects (P < .001) but not normal and nodule subjects (P = .177) or nodule and polyp subjects (P = .246). ROC analysis found that PTF (area under the curve [AUC] = 0.691) and MFR (AUC = 0.684) had a similar diagnostic utility. Conclusions: PTF can be used to differentiate between normal and pathological voices. As a parameter that is experimentally sensitive to the biomechanical parameters providing its theoretical basis, it could be used clinically to analyze laryngeal functionality. Future research could focus on measuring PTF in other pathologies, such as paralysis or scarring, which would also affect the effort required to produce voice. Laryngoscope, 2009 [source] Seasonality in sperm parameters in normal men and dyspermic patients on medical interventionANDROLOGIA, Issue 2 2009D. A. Adamopoulos Summary This study attempted to investigate the presence of seasonal variations in sperm parameters and to evaluate the season's impact on the response to treatment in men with idiopathic oligozoospermia (IO). To this end, a retrospective analysis of the records of 294 men, who participated in a controlled study, was performed. This sample included IO men (n = 106) treated with tamoxifen citrate (10 mg b.i.d.) and testosterone undecanoate (40 mg t.i.d.) or placebo (n = 106) and normozoospermic men (n = 82) serving as controls. Outcome measures included sperm parameters, functional sperm fraction (FSF) and incidence of pregnancy. Analysis showed a raised frequency of high FSF values and increased area under the response curve (AURC) for FSF mean during autumn-winter seasons in patients on active treatment compared with those in placebo (P < 0.05,P < 0.04). Moreover, receiver operation characteristics (ROC) curves for a >100% FSF rise significantly discriminated autumn-winter from other seasons (P < 0.001, all), whereas active treatment showed higher than placebo FSF values particularly during autumn and winter (P < 0.001, all). The pregnancy incidence was higher in the autumn in all groups. It is concluded that FSF values showed a better response to active treatment during autumn and winter, indicating that commencement of empirical treatment at this time in IO men may stand a better chance to succeed. [source] | ||||||||||