Simulation on Foft—Switching PWM Converter with High Power Factor

A new PWM converter based on soft-switching is introduced.The converter uses a minimum number of devices,and requires less switching operations than conventional techniques,Switching is realized solely in a ZVS)zero voltage switching)mode,therefore the loss is reduced and EMI(electromagnetic interference)is suppressed.The paper analyzes the operation of ZVS,and discusses the methods for maintaining a unit power factor and constant DC voltage.Changing the modulation index M and the phase angle θ keeps the input current in phase with the voltage.It also keeps the current sinusoidal,and ensures a constant output voltage.     

Spectroscopic Analysis of Colorants Used for bachiru Carving Technique Found in the Shosoin Treasures

The Shosoin treasures, which include the belongings of Emperor Shomu (CE 701–756) and Empress Komyo (CE 701–760), have an honorable origin and have been continuously handed down for generations since the eighth century in the Todaiji temple in Nara, Japan. Some of the beautiful artifacts found among the treasures display the bachiru carving technique, in which a delicate pattern is produced by carving dyed ivory or antler using additional painting. To elucidate the colorants used for dyeing and painting in the bachiru technique, non-invasive scientific analyses using fiber optic reflectance spectrometry in the visible region, X-ray fluorescence spectroscopy, and X-ray diffraction were performed for eight treasures: a go game board, two go pieces, a nyoi (ritual nail pole), a kugo harp, a bird-shaped accessory, a kaburaya arrow, and a ritual ruler. Second derivatization of the reflectance spectra led to characterization of the dyes in the treasures as sappanwood, lac, madder, gromwell, and indigo. Lac and atacamite were respectively identified in the red and green areas of the painting by reflectance spectrometry and X-ray diffractometry. These results indicated the use of a variety of colorants for the bachiru carving technique in the eighth century.     

THE SIGNIFICANCE OF DEWEY'S AESTHETICS IN ART EDUCATION IN THE AGE OF GLOBALIZATION

On the occasion of Dewey's sesquicentennial anniversary, Kazuyo Nakamura explores Dewey's aesthetics, which holds the plurality of art and culture in high regard. Nakamura develops a theoretical foundation for art education in the present age of globalization based on educational insights drawn from Dewey's aesthetics. The theme of this essay unfolds based on three topics: Dewey's view of the educational value of art in general education, the fundamental viewpoint of art in relation to democracy, and the discussion of the educational aspect of individuality and community with respect to the experience of art. Based on Dewey's aesthetics, this essay presents new perspectives on art education that emphasize the realization of personal values, development of intelligent visual literacy, and enhancement of the quality of communication of art, in the context of globalization.     

Self-selected or imposed exercise? A different approach for affective comparisons

The aim of this study was to compare the psychological and physiological responses of self-selected and imposed sessions of equivalent intensities and durations and allowing to participants a free control of pace during the self-selected session. Seventeen participants completed three sessions on a cycle ergometer. Participant’s VO_2Peak and lactate threshold were measured during an incremental exercise test. During the second and third sessions, participants could view a virtual cyclist on a monitor. During the self-selected session, participants were allowed free control of the intensity and duration. To ensure that the imposed session replicated the self-selected session in intensity, participants were instructed to follow an additional virtual cyclist, which was displayed on a monitor using the CompuTrainer 3D software. Power output and physiological and psychological variables were recorded during the sessions. A two-way ANOVA showed no effect of condition for power output (P = 0.940), heart rate (HR) (P = 0.965), VO₂ (P = 0.898), blood lactate (P = 0.667), Feeling Scale (P = 0.877), Felt Arousal Scale (P = 0.924) and CR100 (P = 0.939). A paired t-test showed no significant difference in Physical Activity Enjoyment Scale scores between sessions (P = 0.054). In contrast to previous studies, the self-selected session did not provide better affective responses than the imposed session with same intensity and duration.     

Gender differences associated with rearfoot,midfoot, and forefoot kinematics during running

Females, as compared with males, have a higher proportion of injuries in the foot region. However, the reason for this gender difference regarding foot injuries remains unclear. This study aimed to investigate gender differences associated with rearfoot, midfoot, and forefoot kinematics during running. Twelve healthy males and 12 females ran on a treadmill. The running speed was set to speed which changes from walking to running. Three-dimensional kinematics of rearfoot, midfoot, and forefoot were collected and compared between males and females. Furthermore, spatiotemporal parameters (speed, cadence, and step length) were measured. In the rearfoot angle, females showed a significantly greater peak value of plantarflexion and range of motion in the sagittal plane as compared with males (effect size (ES)?=?1.55 and ES?=?1.12, respectively). In the midfoot angle, females showed a significantly greater peak value of dorsiflexion and range of motion in the sagittal plane as compared with males (ES?=?1.49 and ES?=?1.71, respectively). The forefoot peak angles and ranges of motion were not significantly different between the genders in all three planes. A previous study suggested that a gender-related difference in excessive motions of the lower extremities during running has been suggested as a contributing factor to running injuries. Therefore, the present investigation may provide insight into the reason for the high incidence of foot injuries in females.     

Analysis of the distances covered and technical actions performed by professional tennis players during official matches

The purpose of this study was to analyse the physical and technical performances of professional tennis players during official matches. The trajectories of eight players were obtained during matches, using an automatic tracking method. The distances covered and technical performances were analysed for the first and second sets. The athletes covered (mean ± standard deviation) a total of 1702.4 ± 448.2 m in the first set, 1457.6 ± 678.1 m in the second set and 3160.0 ± 880.1 in the entire match. No differences were found between the sets for the physical variables (lateral and forward displacements, distance covered per rally, per game and per set, and the percentage of time spent in each range of velocity). However, the distances covered by the athletes during the rallies in which they were serving (median = 5.2; interquartile range (IQR) = 6.7 m) were statistically smaller than when they were returning (median = 6.2; IQR = 7.7 m). Forehand ground stroke proficiency decreased from the first (mean ± standard deviation: 75.2 ± 4.11%) to the second set (mean ± standard deviation = 65.5 ± 14.3%). In conclusion, tennis players did not present reduced physical performance from the first to the second set.     

The sensitivity of the alternative maximal accumulated oxygen deficit method to discriminate training status

The purpose of the study was to investigate the sensitivity of an alternative maximal accumulated oxygen deficit (MAOD_ALT) method to discriminate the “anaerobic” capacity while comparing: least trained (LT) participants (n = 12), moderately trained (MT) participants (n = 12), endurance trained (ET) participants (n = 16), and rugby (RG) players (n = 11). Participants underwent a graded exercise test on a treadmill and a supramaximal effort for assessing MAOD_ALT. MAOD_ALT was calculated as the sum of oxygen equivalents from the phosphagen and glycolytic metabolic pathways. MAOD_ALT was significantly higher (P < 0.05) in RG (64.4 ± 12.1 mL · kg^?1) than in ET (56.8 ± 5.4 mL · kg^?1; effect size [ES] = 0.77; +13.5%), MT (53.8 ± 5.3 mL · kg^?1; ES = 1.08; +19.8%), and LT (49.9 ± 4.5 mL · kg^?1; ES = 1.50; +36.4%). In addition, the magnitude-based inference analysis revealed that MAOD_ALT was likely (LT vs. MT), very likely (MT vs. RG, and ET vs. RG) and most likely (LT vs. ET, and LT vs. RG) different between all groups, except for MT and ET, which presented an unclear difference. In conclusion, MAOD_ALT was sensitive enough to distinguish the “anaerobic” capacity in individuals with different training status, especially for RG players compared with LT participants and MT participants.     

软开关脉宽调制变频技术

In this paper, a new soft-switching inverter using a minimum number of devices, and a new PWM (pulse-width modulation) method suitable for 3-phase soft-switching inverters are proposed. The circuit is used as an interface between the DC supply and the conventional voltage source of a PWM inverter. The number of switching operations can be reduced by using the PWM strategy. Increasing the amplitude of the fundamental component contained in the output waveform results in an effective utilization of the DC supply, a reduction of nominated capacity of the inverter elements, and a reduction of switching loss in the switching devices. Supported by National Natural Science Foundation of China (59977012)     

Influence of regression model and incremental test protocol on the relationship between lactate threshold using the maximal-deviation method and performance in female runners

Abstract

This study examined the influence of the regression model and initial intensity of an incremental test on the relationship between the lactate threshold estimated by the maximal-deviation method and the endurance performance. Sixteen non-competitive, recreational female runners performed a discontinuous incremental treadmill test. The initial speed was set at 7 km · h^?1, and increased every 3 min by 1 km · h^?1 with a 30-s rest between the stages used for earlobe capillary blood sample collection. Lactate-speed data were fitted by an exponential-plus-constant and a third-order polynomial equation. The lactate threshold was determined for both regression equations, using all the coordinates, excluding the first and excluding the first and second initial points. Mean speed of a 10-km road race was the performance index (3.04 ± 0.22 m · s^?1). The exponentially-derived lactate threshold had a higher correlation (0.98 ≤ r ≤ 0.99) and smaller standard error of estimate (SEE) (0.04 ≤ SEE ≤ 0.05 m · s^?1) with performance than the polynomially-derived equivalent (0.83 ≤ r ≤ 0.89; 0.10 ≤ SEE ≤ 0.13 m · s^?1). The exponential lactate threshold was greater than the polynomial equivalent (P < 0.05). The results suggest that the exponential lactate threshold is a valid performance index that is independent of the initial intensity of the incremental test and better than the polynomial equivalent.     

Domestic pigeons (Columba livia) discriminate between photographs of male and female pigeons

We investigated whether pigeons are able to discriminate color photographs of male and female pigeons, using a categorical discrimination procedure. In Experiments 1 and 2B, 10 out of 14 pigeons learned the discrimination. Of these, 5 pigeons showed transfer to novel stimuli, demonstrating the categorical nature of the trained discrimination. Experiment 3 showed that the discriminative behavior was based primarily on the body, as opposed to the head and the neck region. In 1 out of 3 pigeons, the discriminative behavior was maintained by the black-and-white photographs. The results suggest that some pigeons have the ability to discriminate the sex of conspecifics without behavioral cues.