Masaaki Kawahashi

Renovation of Journal of Visualization

The Journal of Visualization has been renovated on 1 January 2010. The Journal was founded in 1998 as a full color journal. In those days, the papers were published in black and white. However, the color images were very important to understand the visualized information. Then, the Editorial Board decided to publish the full-color printing journal. There were very few color journals in 1998. After 12 years of continuous publication by the Visualization Society of Japan (VSJ), the Journal has become one of the top journals in the field of Visualization. The circumstances have also drastically changed. Almost all other journals are published online with color images. In 2008, the VSJ decided the transfer of the publisher to Springer Verlag. Following the contract, the Journal of Visualization has been published by Springer Verlag from this volume, i.e., Volume 13. The Editorial Board was also reconstructed for this renovation. I am the new Editor-in-Chief with the support of Eight Associate Editors. We would like to thank the previous Editorial Board Members for their efforts to improve the Journal, especially Prof. Nakayama, Prof. Tanida and Prof. Kobayashi, former Editorin-Chiefs. The new Editorial Board will also make great efforts to keep or improve the quality of the journal. The scope of the journal is expanded to more wide fields. The scope includes Information Visualization, Data Visualization, Flow Visualization, System Visualization and so on. Any papers related to the VISUALIZATION will be published in this journal. VISUALIZATION is the keyword to solve many problems in the 2010s, such as Global Warming, Energy Security, Knowledge Management and so on. The Journal of Visualization will be growing to be a world top journal in the field of Visualization.

Experimental investigation of viscous effects upon a breakup of droplets in high-speed air flow

The deformation and disintegration of water and silicone oil droplets were investigated experimentally in a shock tube. Optical visualization was performed by means of the shadowgraph method. Droplets with diameters in the range of 200 to 500 μm were generated by an oscillating capillary. The smallest Weber number in the present experiments is close to the critical value of the breakup. The droplets disintegrated in the stamen or bag mode for moderate values of the Weber number. The effect of the viscosity of the liquid on the breakup mode and the breakup time is discussed.

Experimental analysis of pendelluft flow generated by HFOV in a human airway model.

HFOV (High frequency oscillatory ventilation) is an effective artificial respiration technique for the treatment of pulmonary disease patients. In HFOV, the pendelluft is one of the important factors in gas transport and mixing mechanisms. Experimental analysis of the pendelluft flow generated in a bronchial tube model of single bifurcation with different volume ratios of daughter branches has been carried out by using time-resolved micro-particle image velocimetry obtaining instantaneous velocity distributions of oscillatory flows in the bronchial tube model at a frequency range of 10-15 Hz. Based on the oscillatory velocity profiles changing with time for different frequencies, the pendelluft phenomena have been discussed.

An Improved, Free Surface, Topographic Technique

Current techniques of water wave visualization such as shadowgraphy and stereo photography are widely used but are deficient in many aspects. Refraction based visualization observes the bending of light as it traverses across a liquid-air interface. This work describes the continued development of techniques to measure the surface height of a liquid free surface. The method, Reference Image Topography, utilizes refraction of light at the free surface as a function of the local angle of that surface. Particle Image Velocimetry (PIV) software is used to evaluate apparent dislocations of the target image viewed through the free surface, which are approximately proportional to the surface angle. High-resolution images are presented of the dynamic surface topography for a point source and the shallow water flow around a vertical cylinder.

White-light speckle method for obtaining an equi-velocity map of a whole flow field

The surface of a flow seeded with aluminium oxide particles is photographed with two pulsed illuminations of whitelight. When the resultant double-exposure specklegram is optically processed using a spatial filtering technique, an equivelocity pattern can be obtained. Especially, a coloured display of the pattern by the white-light reconstruction gives many useful informations about the flow state.

ENGINEERING IMAGING : USING PARTICLE IMAGE VELOCIMETRY TO SEE PHYSIOLOGY IN A NEW LIGHT

1 Despite the array of sophisticated imaging techniques available for biological applications, none of the standard biomedical techniques adequately provides the capability to measure motion and flow. Those techniques currently in use are particularly lacking in spatial and temporal resolution. 2 Herein, we introduce the technique of particle image velocimetry. This technique is a well‐established tool in engineering research and industry. Particle image velocimetry is continuing to develop and has an increasing number of variants. 3 Three case studies are presented: (i) the use of microparticle image velocimetry to study flow generated by high‐frequency oscillatory ventilation in a human airway model; (ii) the use of stereoparticle image velocimetry to study stirred cell and tissue culture devices; and (iii) a three‐dimensional X‐ray particle image velocimetry technique used to measure flow in an in vitro vascular flow model. 4 The case studies highlight the vast potential of applying the engineering technique of particle image velocimetry and its many variants to current research problems in physiology.

Experimental Analysis of Oscillatory Airflow in a Bronchiole Model with Stenosis

As the mechanism of gas transport and exchange in human respiratory ventilation, the complicated processes of mixing and diffusion in airways of human lungs are considered. However the mechanism has not been clarified enough. On the other hand, the analysis of detailed mechanism in the case of artificial ventilation like HFOV (High Frequency Oscillatory Ventilation) is strongly required for the development of clinical treatments on patients with respiration disorder. In HFOV, it is considered that pendelluft becomes one of the important factors of gas transport and exchange because of high frequency ventilation in comparison with natural breathing. As increase of the frequency, the different time constants of lung units generate phase lag of ventilation in airways of lungs. The phase lag of ventilation causes to generate pendelluft. The time constant is determined by compliance and flow resistance of lung unit. In order to investigate the effect of the different time constants induced by the difference of flow resistance in a part of respiratory bronchiole of human lungs, the experimental study has been carried out by using multi-bifurcated micro channels as a model of bronchiole. The flow resistance in the model channels was produced by a stenosis. The velocity distributions of ventilation flows in the channels with and without the stenosis have been measured by using μ-PIV technique. The results obtained show the frequency effects on the flow pattern in the bronchiole model channels and the appearance of pendelluft.

Simultaneous measurement method of size and 3D velocity components of droplets in a spray field illuminated with a thin laser-light sheet

A measurement technique to simultaneously obtain the size and 3D velocity components of droplets in a spray field illuminated by a thin laser-light sheet has been proposed. This technique is based on the optical processes of in-focus and out-of-focus imaging of spray droplets using a stereoscopic camera arrangement. The patterns obtained by this technique represent the distributions of glare-point pairs and defocused images with interference fringes generated by the imaging of reflection and first-order refraction rays scattered from each droplet illuminated by the laser light. The size of a droplet is evaluated by the glare-point separation and the fringe order of the interferogram. The velocity of each droplet is obtained by 3D particle tracking velocimetry (3D-PTV) based on the tracking of the glare-point pair and the defocused image generated by a droplet. For this technique, the three-dimensional optical arrangement corresponding to the scattering angle and the stereo-viewing angle, and the algorithm for stereoscopic matching of both images have been developed. The accuracy of this technique for the size and 3D velocity measurements was evaluated by applying a calibration technique, and the feasibility of this technique has been confirmed by applying it to the measurements of a spray field issuing from a swirl nozzle. From the results obtained, it has been verified that the error in the size measurement is within 1.5% and that for the velocity measurement is less than 3%.

Automatic processing of Young's fringes in speckle photography

Abstract A new method for the automatic processing of Youngs fringes in speckle photography is described, based on the technique of spatial phase detection. The amount of calculation is reduced, yet accuracy is of an order comparable with that of the Fourier transform method. Furthermore, orientation of fringes is determined as well as fringe spacing.

Experimental Investigation of Oscillatory Air Flow in a Bronchial Tube Model with HFOV Mode

Mechanical ventilations for artificial respiration have been developed to improve the medical treatment of the patients showing respiratory disorder. In various types of ventilation, High Frequency Oscillatory Ventilation (HFOV) is one of the most effective techniques of medical care for pulmonary disease patients, especially, infantsor premature infants. HFOV is a ventilation technique with high breathing rate in comparison with the normal breathing rate. Some successful studies have focused on the effect of treatment using HFOV However, the mechanism of gas exchange in bronchial tube under the medical treatment by HFOV has not been clarified. In this study, the oscillatory flow in a micro-channel model of bronchial with single bifurcation in HFOV mode has been investigated experimentally with micro Particle Image Velocimetry (micro PIV) technique. The phase averaged velocity profiles changing with the driving frequency of HFOV have been inves tigated.