Boiling Heat Transfer and Pressure Drop of R1234ze(E) inside a Small-Diameter 2.5 mm Microfin Tube

Currently, the development of high-performance and compact heat exchangers with small- diameter tubes having a hydraulic diameter of less than 5 mm is needed in order to improve the performance of the heat exchanger and to reduce the refrigerant charge for air-conditioning systems. The effects of surface tension and shear stress on boiling heat transfer and flow characteristics become dominant as the tube diameter decreases. In addition, these effects are different from those in conventional-diameter tubes. It is necessary to clarify boiling heat transfer and pressure drop to facilitate the design of evaporators. Furthermore, low global warming potential refrigerants such as HFOs have been attracting attention. However, only limited research is available on the boiling heat transfer and pressure drop of HFO refrigerants in small-diameter microfin tubes. This study experimentally investigated the boiling heat transfer and pressure drop of R1234ze(E) in a horizontal small-diameter microfin tube having 2.5 mm outer diameter and 2.1 mm equivalent diameter. The boiling heat transfer and pressure drop were measured in a mass velocity range of 100–400 kg/(m2s) and heat flux range of 5–20 kW/m2 at a saturation temperature of 15°C. The boiling heat transfer coefficient at the mass velocity of 200 kg/(m2s) exhibited the highest value at the dominant region of tin liquid film evaporation heat transfer. The measured boiling heat transfer coefficient agreed well with previous correlations in only the dominant region of forced convection evaporation. The frictional pressure drop increased with increasing mass velocity and vapor quality. The measured pressure drop agreed well with previous correlations for conventional-diameter microfin tubes

Development of new methods to calibrate centre of pressure obtained from force platform

Kinetics and kinematics data are measured using force platforms and three-dimensional cameras in the gait analysis laboratory. Reducing errors related to the force platform when collecting data was necessary. This study describes a new calibration method for centre of pressure of laboratory force platforms using a sandal with extended bar. Firstly, a subject was asked to put his weight vertically on various places of the force platforms using the sandal to create a correction table. Secondly, nine validation trials were conducted to examine the accuracy of the force platforms after correction. The data taken from the centre of pressure and the motion capture were analyzed. Then the erroneous position of the centre of pressure data was translated to the correct position by using weighted average of the vector mostly close to the validation point. The method used in this study allowed to reduce the maximum error from 24.6 mm to 2.7 mm

Rapid Amygdala Gamma Oscillations in Response to Eye Gaze

Background: The eye gaze of other individuals conveys important social information and can trigger multiple psychological activities; some of which, such as emotional reactions and attention orienting, occur very rapidly. Although some neuroscientific evidence has suggested that the amygdala may be involved in such rapid gaze processing, no evidence has been reported concerning the speed at which the amygdala responds to eye gaze. Methodology/Principal Findings: To investigate this issue, we recorded electrical activity within the amygdala of six subjects using intracranial electrodes. Subjects observed images of eyes and mosaics pointing in averted and straight directions. The amygdala showed higher gamma-band oscillations for eye gaze than for mosaics, which peaked at 200 ms regardless of the direction of the gaze. Conclusion: These results indicate that the human amygdala rapidly processes eye gaze

Measurement of radon and thoron concentrations in the Tokyo Metropolitan University Arakawa Campus building

Smoking and radon inhalation are the primary causes of lung cancer in many countries. The world average annual dose due to radon inhalation is 1.26 mSv y^, which is more than half of the annual exposure dose from natural radiation sources, 2.40 mSv y^. In this study, radon and thoron radioactivity concentrations（ hereafter referred to simply as concentrations） measurements were carried out in the Tokyo Metropolitan University Arakawa Campus building using a pulse type ionization chamber and passive radon and thoron discriminative monitors. The respective average （±σ） radon concentrations （Bq m^） for each day of the week from Sunday to Saturday were: 21 ± 7, 20 ± 7, 20 ± 8, 22 ± 6, 21 ± 7, 20 ± 6, 23 ± 7. On week days, the radon concentration peaked daily at 8:00 am with a value of 25 ±6 Bq m^, it decreased until 7:00 pm reaching a value of 17 ±7 Bq m^, and then, showed a rising trend to the next morning’s peak. Radon concentration tended to show a higher value and less fluctuation on weekends. No seasonal change was observed. No correlation was observed between radon concentration and thoron concentration. In Japan, the repor ted arithmetic average radon concentration indoors is 15.5 Bq m^ and the arithmetic average concentration outdoors is 5.4 Bq m^. The annual effective dose of radon by inhalation in Japan is 0.64 mSv y^. The average radon concentration of reinforced concrete buildings tends to be higher, though a radon concentration survey in reinforced concrete buildings in Japan is lacking. Calculated annual average exposure dose in the campus reinforced concrete building was 0.15 mSv y^. Annual average exposure dose considering an indoor environment other than the Arakawa Campus building was 0.42 mSv y^