Realization of the powering/regenerative operation of the induction motor by the parallel resonant power converter and proposal of a novel circuit topology

A resonant power converter for the low switching loss power conversion must be achieved for high-frequency zero voltage switching or zero current switching. The important matters of the continuation of resonant phenomena are the control strategy of resonant initial current and the clamp circuit for suppressing the resonant link voltage. The control strategy of the resonant initial current is discussed and the powering and regenerative operation are shown successfully in the steady state and transient state by experimental test. Finally, a new resonant dc link dual converter system is proposed and it is confirmed that the voltage stress of the resonant capacitor and the rms value of electrolytic capacitor current are decreased with experimental test also.     

Robust State Observer and Variable Sampling Technique for Performance Improvement of a Motor Drive System

A microprocessor-based digital control system of motor speed is discussed with respect to the dynamic response and the accuracy of controlled speed. Two methods for improving both the dynamics and the accuracy are examined in this paper. One is a method of variable gain state observer and the other is a variable sampling technique. Comparing their effects in improving the accuracy of controlled speed, it is shown that the former is preferable to the latter. The validity of the above discussion is confirmed by several simulations.     

A new approach for minimum-torque-ripple maximum-efficiency controlof BLDC motor

Torque-ripple control of the brushless DC motor has been the main issue of the servo drive systems in which the speed fluctuation, vibration, and acoustic noise should be minimized. Most methods for suppressing the torque ripples require Fourier series analysis and either iterative or least-mean-square minimization. In this paper, a novel approach to achieve ripple-free torque control with maximum efficiency based on the d-q-0 reference frame is presented. The proposed method optimizes the reference phase current waveforms which include the case of three-phase unbalanced conditions. As a result, the proposed approach provides a simple way to obtain optimal motor excitation currents. The validity and practical applications of the proposed control scheme are verified through the simulations and experimental results     

Pleiotropic deficiencies of the laccase-derepressed mutant lah-1 are caused by constitutively increased expression of the cross-pathway control gene cpc-1 in Neurospora crassa

PURPOSE: To estimate gamma-ray doses received by Hiroshima atomic bomb survivors using electron spin resonance (ESR) of tooth enamel and to compare the results with cytogenetic data. MATERIALS AND METHODS: Tooth enamel ESR was performed for 100 teeth donated from 69 Hiroshima survivors, and conventional cytogenetic examinations were conducted for 61 of the tooth donors. To evaluate possible contamination from dental X-ray exposure, which primarily affects the tooth's buccal surface, each tooth was divided into buccal and lingual parts for subsequent independent enamel isolation and ESR measurement. RESULTS: Almost 20 teeth showed considerably larger buccal doses than lingual doses, but most of these discrepant teeth were incisors and canines. The results are probably attributable to solar light exposure. In contrast, the buccal and lingual doses found in molars were similar. Conventional translocation data of lymphocytes and ESR-estimated doses of 40 donors of molars showed the dose-response for translocations to be almost the same as that expected from in vitro gamma-ray irradiation experiments. CONCLUSIONS: Both tooth enamel ESR and lymphocyte cytogenetics are useful measures for individual biodosimetry of acute radiation exposure, even half a century after the exposure occurred.     

Real-time video-based modeling and rendering of 3D scenes

Our work targets 3D scenes in motion. In this article, we propose a method for view-dependent layered representation of 3D dynamic scenes. Using densely arranged cameras, we've developed a system that can perform processing in real time from image pickup to interactive display, using video sequences instead of static images, at 10 frames per second. In our system, images on layers are view dependent, and we update both the shape and image of each layer in real time. This lets us use the dynamic layers as the coarse structure of the dynamic 3D scenes, which improves the quality of the synthesized images. In this sense, our prototype system may be one of the first full real-time image -based modelling and rendering systems. Our experimental results show that this method is useful for interactive 3D rendering of real scenes     

Expectation effect of perceptual experience in sensory modality transitions: modeling with information theory

A user’s experience of a product involves a set of state transitions. For example, the state of a sensory modality may shift from vision to touch to perceive a quality of a product. Between such state transitions, users expect experiences of the subsequent states as well as experience the current state event. A discrepancy between prior expectation and posterior experience evokes emotions, such as surprise, satisfaction, and disappointment, affecting the perceived product value. A noteworthy psychological phenomenon is that expectation affects perceived experience. This phenomenon, called the expectation effect, is a key to designing the affective experience of a product. Although experimental findings of this effect exist in a variety of disciplines, general and theoretical models of the effect are largely unexplored. In this paper, we propose a theoretical model of the expectation effect using information theory and affective expectation model. We hypothesize that Shannon’s entropy of prior subjective probability distributions of posterior experience determines the occurrence of an expectation effect, and the amount of information gained after experiencing a posterior event positively relates to the intensity of the expectation effect. Furthermore, we hypothesize that the conscious awareness of expectation discrepancy discriminates the two types of expectation effect, assimilation and contrast. To verify these hypotheses, we conducted an experiment using the tactile quality of surface texture. In the experiment, we extracted the visual expectation effect on tactile roughness and analyzed the causes of the effect based on these hypotheses. The experimental results validated the proposed model.     

Foreign Object Damage Resistance of Silicon Nitride and Silicon Carbide

To clarify the foreign object damage (FOD) resistance of ceramics, chipping fracture mode and flexural fracture mode were investigated using several types of Si₃N₄ and Sic. The critical velocity which is the threshold impact velocity of the projectile for chipping fracture and flexural fracture was determined. The critical velocity of the chipping fracture mode is explained as a function of K ^5/2_IC a ^–5/4, and depends on the hardness and the shape of the projectile. The critical velocity of the flexural fracture mode is explained as a function of σ^5/6_C t ^5/3. The mechanisms of impact damage are discussed.