With the spread of the Internet, construction of systems that supplies the new communication fields for citizen is performed on the network in domestic and foreign cities. These systems have been examined in Numazu-city in Japan. Begin with, the institutions locates in the city were made by VRML (Virtual Reality Modeling Language) and the inside of three-dimensional space could be inspected freely passing through the Internet. Moreover, the tool that can be made realistically these institutions was developed. The contents that have been made are Gen Yamaguchi virtual museum, Numazu Imperial Villa, Bokusui Wakayama Memorial Hall, Nakamise Virtual Shopping Street, Numazu Station Plaza and Numazu Campus of Tokai University. The subject after this is to develop new system to retrieve easily these contents and the interface easy to use. Moreover, expanding to the information of administration, protection against disasters, welfare, etc., these contents are planned to expand the information system that can enlarge the network among a resident of city.

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In this report, an image processing system is applied to extract a vehicle motion on an urban arterial street. A vehicle motion is exactly determined using spatial differentiation and frame subtraction in the image processing. Desired speed-density data are obtained by eliminating data with large standard deviation in linear approximation for vehicle position-time. The results show that speed-density data are scattered at low speed in the relation of speed-density on the urban street. Speed-density data and flow-density data on the street are approximated by a generalized exponential model. And then the critical flow and density of the urban street are determined.

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In this paper, a non-pulsating jet and a pulsating jet are researched experimentally and the experiment data are analyzed with a PTV (Particle Tracking Velocimetry) method. The velocity fields are measured accurately and efficiently with a PTV method based on fuzzy logic although the strong shear and turbulence appear in the jets. Based on the measured velocity fields, the distributions of mean velocity, mean vorticity, shear strain rate and kinetic energy are compared between non-pulsating and pulsating jets in order to analyze the different flow features between the two kinds of flow fields.

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PIV (Particle Image Velocimetry) is widely applied to analyze complex flows. The velocity fields obtained by PIV, however, contain some unmeasurable areas. In particular, three-dimensional PTV provides sparsely distributed velocity vectors in principle. It has been required accordingly to develop the whole field estimation methods and we have proposed an estimation method using artificial neural networks for two-dimensional flows.
This paper presents two new estimation methods for three-dimensional flows which is based on previously proposed one. The neural networks in the methods learn the whole field velocity distribution from PIV-measured one so that the estimated velocity vector fields agree with measured one in the original field and satisfy the continuity equation of flow. We additionally evaluate the proposed methods by applying them to the three-dimensional PIV standard images.

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PIV technique is generalized from the viewpoint of identification problem of flow field. The process of obtaining velocity distribution in image measurement can be considered as a parameterization problem of dynamical system. A PIV technique based on physics is described. The results are given as the solution of the optimization problem. In order to obtain the solutions effectively, the Evolutionary Computation, which emphasizes mutational transformations that maintain behavioral linkage between each parent and its offspring, respectively, at level of the species, is developed. The Algorithm, such as genetic operator, is constructed using knowledge for the problem. The present method is applied to the cavity flow compared with the results by Computational Fluid Dynamics. The results show the good agreement with the target solution.

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In recent years, various methods which attempt to reduce measurement errors and supplement data to data omission points by applying governing equations have been proposed. In this paper, we classify these methods according to the types of observations and equations used.
Subsequently, we propose GCFM (Generalized Cost Function Method) which reflects the observation data of velocity, temperature and mass concentration to the mutual estimation of each field by using the cost function defined by the summation of the residuals of governing equations and data corrections.
Finally we execute a numerical experiment for 2-dimentional steady non-isothermal flow field which contains pollutant emission sources to verify the effectiveness of GCFM, and we can confirm that our method is effective in the grasping of the flow fields.

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It is important to grasp whole velocity field and temperature field when evaluating air conditioning room environment. However it is difficult to obtain data of whole room even when we use PIV technique, except for a room model built for experimental purpose.
In this report, we attempt to interpolate and correct measured data which is discrete and partial by using the governing equations of flow field. We excuted an experiment for an air conditioning room of 3-dimensional steady flow field including heat source, and measured velocity distribution by using PIV for smoke image and temperature by thermocouples. Subsequently, we estimated whole flow field from the obtained data and the governing equations by using GCFM (Generalized Cost Function Method) which reflects the information of measured data to the mutual estimation of each field.

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Microfluidics and micro-flow-measurement are recent topics relating to different fields of engineering and science, such as micro-circulation in living body, flow through micro-channel for medical use, micro-flow mixing, micro-jet, flow in porous media, flow around electronic device, flow around micro-machine, chemical reaction and molecular design. In micro-flow analysis, physical characteristics, which are particular to the micro-flow, must be considered. And also experimental method is different from it for general flow problems. Micro-PIV is useful to velocity field measurements of micro-flow phenomena, however, practical technique of it has not been established in detail. Velocity distribution of flow through a micro-channel is measured by using micro-PIV system, and fundamental characteristics of the tracer image obtained by using macro lens and CCD camera are investigated in this report.

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Dilute solution of high polymer in water is known to bring about a drastic drag reduction of turbulent shear flows. Some previous studies have shown that the rate of drag reduction in a pipe for a constant Reynolds number is enhanced with decreasing pipe diameter, indicating that the size of the flow geometry can be an important parameter. In the preset study, a series of flow visualization and PIV measurement of velocity distributions in a micro channel flow of dilute high polymer solution have been performed to understand the relationship between the drag reduction and the characteristics of micro channel flow.

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Though evaluation of thrombus formation for blood pumps dependeds on animal experiments, flow visualization analysis would be able to assist or to save animal experiments. Using a scale-up pump model and 4-time particle tracking velocimetry software, correlation study was conducted between thrombus contour and relative stagnation contour for two kinds of centrifugal blood pumps. It was found that impeller surface with small relative velocity has a close correlation with platelet deposition or thrombus formation.

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The turbulent behavior of a turbulent combined-convection boundary layer along a vertical heated plate in air has been experimentally investigated by using a particle image velocimetory (PINT). The reliability of turbulence measurements with a PIV for low-speed turbulent boundary layer flow in air is confirmed by comparison between fluctuating velocities measured with a PIV and a hot wire in the natural-convection boundary layer. Turbulence quantities measured in the combined-convection boundary layer show that the intensity of velocity fluctuation, especially in the outer layer, decreases with a slight aiding freestream. For the instantaneous velocity vectors, large-scale fluid motions moving from the maximum mean velocity location to the edge of the boundary layer are intermittently observed in the outer layer, and such fluid motions mainly generate turbulent energy of the boundary layer.

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In recent years, river flow measurements have been successfully conducted using image analysis techniques. Aerial photographs were the first used for this kind of measurements. However, only instantaneous data are obtained from aerial photographs, without any information on the time-dependent flow feature. Video images taken from a riverbank or a bridge are also useful for capturing long-term river flow phenomena but the spatial resolution is limited due to the shallow viewing angle. Utilization of video images from a helicopter is another possibility for achieving better and uniform spatial resolution of river flow measurements. In this study, a windows application capable of capturing river surface flow from helicopter images using PIV technique is developed.

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Open-channel flow at a backstep displays a complicated flow feature as it involves a free water surface easily deformed by the pressure field in the separation zone. The flow changes from subcritical to supercritical flows at the backstep section and a hydraulic jump is created downstream of it when a tail water depth is favorably controlled. The flow becomes much more complicated in the case a cavity is installed at the backstep section for the purpose of energy dissipation. The energy dissipation becomes greater as the cavity length increases. In this study, the velocity field was measured in detail by the particle tracking velocimetry technique (PTV) for various aspect ratios of the cavity. It was made clear that the energy dissipation is closely related to turbulence in the cavity and periodic oscillation of a hydraulic jump occurs for a specific aspect ratio of the cavity.

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The dynamic threshold binarization method is quite useful for the detection of individual particle images in the particle tracking velocimetry, as well as for a certain type of peak detection in the two-dimensional signal processing. One of the drawbacks of the basic algorithm of this method is the computing time required for the iteration of binarization and labeling. So in the present study, a quick algorithm for this method is proposed in the place of the basic one. With this quick algorithm, the computing time is reduced by 1/3 to 1/4 of the basic algorithm.

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Recently, many researchers propose interpolation methods for PTV (Particle Tracking Velocimetry) data because the spatial distribution of physical quantities can not be directly obtained by PTV. These interpolation methods use mathematical or physical logic-based algorithms, and their accuracy are evaluated by several physical quantities. However, the evaluation methods are not generalized. In the present report, evaluation methods which use the equation of continuity and Navier-Stokes equation are discussed, and some post-processing methods proposed by authors are examined by the new evaluation methods.

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The “classical” PIV technique is only capable of recording the projection of velocity into the plane of the laser sheet, i.e the out-of-plane velocity component is lost while the in-plane components are affected by an unrecoverable error due to the perspective transformation. For highly three-dimensional flow fields like lobed jet mixing flow, this may lead to substantial measurement error of the local velocity vector. In order to get the velocity three-components simultaneously to reveal the interaction and evolution of various vortices in the lobed jet mixing flow, a high-resolution stereoscopic PIV system is used in the present study to measure the near flow field of a lobed jet mixing flow. Based on the analyzing of the three-components and three-dimensional velocity fields of the stereoscopic PIV measurement results, the mixing characteristics in the lobed jet mixing flow is studied and the mechanism of the mixing enhancement in lobed jet mixing flow is discussed.

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In this paper we present the study on a three-dimensional PTV measurement of bubbly flow with color digital image processing. The tracers for the liquid motions shine with yellow-green by an ultra-violet illumination. The bubbles are shadow of the incandescent lights with red-colored cellophane sheets. By using six mirrors we lead the image of the test section seen from different three directions to a high-speed color video camera. Color digital image processing makes the bubbles and tracers extracted from background light. We calculate the velocity vectors, trajectories and the three-dimensional characteristics of the bubbles. We reconstruct the whole bubbly flow and present one by OpenGL.

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The flow field in a gas turbine combustion chamber was investigated experimentally by using a high-resolution PIV system. The shedding of vortices around the flamer holder in the combustion chamber was visualized quantitatively from the PIV measurement results. The PIV measurement results were also compared with LDV data and Large Eddy Simulation (LES) results to verify the present investigation.

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Dynamic programming matching technique, which is used for the voice recognition, has been adopted to the time line images obtained by the spark tracing method for the high speed air flow. As the high voltage sparks between two electrodes trace the air flow very well, we can measure the two or three-dimensional air velocities, if we can quantify the displacement and the time interval between sparks. With the dynamic programming matching technique, the characteristics of the two consecutive spark lines are nicely corresponded and thus the three-dimensional displacement between sparks are quantified. Presently, the high speed air jet has been measured with this technique.

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Previously, we have proposed a quasi-analytical electromagnetic filed computation methodology, which has made it possible to compute the complex electromagnetic field distributions not obtainable by the conventional numerical schemes, such as finite elements and boundary elements means. However, because of the displacement current, our quasi-analytical method encounters a some difficulty when analyzing the high frequency electromagnetic field distribution. To overcome this difficulty, we are now developing a new quasi-analytical approach taking the displacement currents into account. In the present paper, in order to reduce a computational load of our method and to obtain a good approximate solution, we apply the wavelet transform method to our system of equations. As a result, it is found that the wavelet transform method yields a good solution when exciting by the relatively low frequencies.

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This paper proposes a Lissajous's diagram visualization method based on a multi-resolution analysis of the discrete wavelets. We apply our approach to a signal processing of a differential type magnetic position sensor for the metallic objects. We apply a wavelet transform to the sensor output signals in order to work out a Lissajous's diagram. As a result, we have succeeded in extracting the distinct signal characteristics. Thus, it is revealed that our Lissajous's diagram methodology based on the wavelets transform may become one of the distinguished methodologies for a signal processing technique.

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Wavelets transform becomes a quite popular tool for analyzing the time domain signals and for the image data compression. On the other side, numerical analysis of various vector field problems becomes also a quite sophisticate methodology with the developments of modern high performance personal computers. Previously, we have reported that the wavelets transform is applicable to the numerical analysis of the vector fields regarding a system matrix as a two-dimensional image data. However, it has been pointed out that the wavelets transform could not apply to the two-or three-dimensional vector field analysis. To overcome this difficulty, this paper tries to apply the wavelets transform approach to a two-dimensional magnetostatic field problem. As a result, it is shown that the wavelets transform yields a fairly good approximate solution depending on the arrangements of system equation, even if the two-dimensional vector field problems.

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We are now exploiting a magnetic sensor, which detects magnetic materials embedded into the ground and concrete walls. Our magnetic sensor is composed of the mechanically vibrating DC magnet having the sensing coils. When there are no metallic materials in the DC vibrating magnetic field, no magnetic field distortion senses no magnetic materials. However, if there is a kind of metallic materials in the DC vibrating magnetic field, then the magnetic field distortion induces a signal at the sensing coils. Analysis of this sensor signal leads to the physical properties of the target metallic material. In the present paper, we propose a method of analysis for magnetic sensor signals. Based on the physical characteristic value such as a time constant of the electric circuit, our methodology tries to work out an equivalent characteristic value reflecting the physical property of the target metallic material. As an initial experiment, we have carried out an evaluation whether the target metallic material is a magnetic or non-magnetic material. As a result, we have succeeded in cognition of the magnetic and non-magnetic materials. Thus, second stage of our smart magnetic sensor developing is reduced into the equivalent characteristic data compression technique employing the discrete wavelet transform. Thus, this paper reports that our characteristic data may be compressed in a quite small data quantity by means of the wavelets.

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We are developing a magnetic domain measurement device under a controlled magnetic field distribution. This work is essentially reduced into solving for an ill-posed inverse problem, because available information is a set of desired magnetic field components caused by a current distribution to de determined. When a number of magnetic field components is greater than those of current components, it is possible to apply a conventional least squares mean under the fixed design variables. In order to work out the optimal design parameters, it is essential to use an objective function, which indicates a fitness parameter between the desired and generated magnetic field distributions. In the present paper, we set up a fitness parameter by means of the multi-resolution analysis of a discrete wavelet transform. As a result, the multi-resolution analysis of the discrete wavelet transform becomes an effective tool for the optimal design of the magnetic field control devices.

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Modern magnetic sensors such as eddy current sensor are widely used for the non-destructive testing to search for the defect and crack in the metallic materials constructing the aircraft, ship, bridge and so on. Recently, flat shape magnetic sensors having high sensibility are required to check up the quality of iron sheets, because only small defect or crack invokes a deterministic fault cans used for the drinks, e.g. beer, cokes and fruit juice. We are now developing a flat shape magnetic sensor to respond such a requirement. Sensibility of our magnetic sensor mainly depends on the rate of inductances between the off and on target magnetic material. This means that we have to carry out the inefficient inductance computations changing various design parameters. Since the value of inductance change greatly depends on the magnetic flux distribution at the vicinity of target magnetic material, then it is possible to design the magnetic sensor in a quite efficient manner when evaluating the feature of magnetic field distribution. In the present paper, we apply a multi-resolution analysis to the change of magnetic fields at the vicinity of target magnetic material. As a result, a homogeneous magnetic field change between off and on target dominates the change of inductance value.

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A method for change detection of multi-temporal satellite images based on Multi-Resolution Analysis is proposed. The method allows to detect changes and is not sensitive to geometric distortions included in the satellite images. The experimental results with simulation image and a Landsat Thematic Mapper (TM) image show that more appropriate changes can be detected with the proposed method in comparison with the exsting method of subtraction.

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An introduction of objects oriented data analysis environment designed by Bell Lab., S language, and its enhanced product, S-PLUS. S-PLUS is now used in processing of data, exploratory data analysis, and data visualization in over 3000 domestic site. S+WAVELETS, developed for wavelet analysis using S language, is add-on module of S-PLUS.

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The colors on picture books by Dick Bruna have been analyzed by using computer.
Fundamental colors including red, blue and green specified by Bruna himself are revealed to be not pure fundamental colors. These picture books have taken reposeful colors that mixed one fundamental color to another fundamental one. The thread of narrative is made a development along the changes of these reposeful colors that increases the charm of picture books by Bruna.

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New objective method for psychological receptivity to culture gaps has been developed using Saitoh discrete wavelets. With this method, 21 letters by a student studying abroad have been analyzed. Both W-curve line and twice shock waves for cross-fertilization in cultures were shown, which has been supported as a common fact theoretically. This is in agreement with subjective hypnosis by Atkinson and Gullhorn.

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The extraction of inexpressive facial information has been carried out by applying RGB convolution (i.e., the convolution of each color component, Red Green and Blue) to the Saito Fourier-Wavelet transforms. Pictures of a child's two different facial expressions, normal and smiling, were transformed separately for each color component. The data from this transformation was analyzed, to find differences between normal faces and smiling faces, which were commonly observed in the convolution of the three colors. RGB convolution could show slight differences in facial information that the monochrome data could not reveal This method has considerable potential for extracting slight facial information of autistic children.

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The aim of this study is creating a music retrieval system whose database employs “atmospheres” of music as its components. For the purpose, an atmosphere of music must be represented on computers. In the report symbols of atmospheres are represented by spectral patterns of music drawn on time -frequency planes. Because such information like harmonies of music, which have great influence on an atmosphere, is included only in raw sound data, not in MIDI nor other compressed data. The wave let transform is selected as a transform method because it is suitable for detecting fine differences of harmonies. The drawings of time-frequency planes indicate the possibility of showing atmospheres of music being represented by the method.

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This paper proposes a wavelet-based asker identification system for smart multi-point tele-conferences. Our system is composed of three processors. The first processor is called an “ask” action detector, which is used to decide whether an “ask” action is occurring. If an “ask” action is detected, the input image is sent to the face detector that detects the human face from the complex background. The detected face is fed to a wavelet-based face identification processor to recognize the asker.

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When the periodic velocity fluctuation is introduced in the mean flow, the separation flow changes in various manners. This report concerns with the “flapping” motion of the separation shear layer by means of the phase averaging of instantaneous velocity profiles over the separation region. In order to know the principal motion of the velocity profile precisely, wavelet transform with Morlet wavelet is used. The shapes of profile are quite different at each phase and with the frequency of the fluctuation. When the suitable frequency was chosen, the phase averaged velocity profile is changing periodically between the profile of “inflection type” and “boundary layer type”.

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Fluctuating velocity in the near wake of a rectangular parallelepiped was analyzed by wavelet transform as well as fast fourier transform. Monet wavelet was used as a mother wavelet. In this paper, we focus on characteristics of fluctuating velocity at three different points; in outer region of wake, in middle region and in stagnant region behind the object. It is shown that relations between predominant fluctuation and secondary fluctuation of high frequency are quite different at each point.

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The behavior of organized motion in an open-channel flow over a concave bed is analyzed by using wavelet transforms. Experimental data of the velocity are obtained by a particle image velocimetry (PIV). Before detecting coherent structures, we employ a maltiresolutional analysis (MRA) for evaluating the accuracy of the PIV velocity data. The high frequency components of the velocity time-series suffer from noise data, so that we reconstruct the velocity time-series without the high frequency components. Then, the distributions of moduli of the velocity fluctuation vectors are analyzed using a two-dimensional continuous wavelet transform (2D-CWT) to extract the organized motion. The spatial scale and location of the organized motion are detected from the maximal values of the wavelet coefficients. The result suggests that the wavelet transform is a useful tool for analyzing the organized motion of this flow.

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An electronic imaging system for visualizing dynamic phenomena is described. The system has several functions of real-time signal processing and had been used at JRR-3M for joint application experiments.

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In the field of non-destructive testing, simultaneous data taking for both neutron radiography and gamma ray radiography is effective because each image has complementary information. This was demonstrated with a two colors fluorescence converter, optical filters, and a CCD camera, by applying static n-γ radiography. Also a dynamic n-γ radioscopy system has been develop and dynamic video data were obtained at TNRF2 of JRR3M

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Fast neutron radiography is an attractive nondestructive inspection technique because of fast neutron's excellent penetration characteristics in matter. However, the difficulty in fast neutron detection reduces the attractive. For capturing a fast neutron image as quickly and efficiently as possible, imaging plates were applied to fast neutron radiography. Simple combination of two pieces of imaging plates and a piece of polyethylene sheet was examined with the FTG discriminator proposed by Yoneda et al. for fast neutron, thermal neutron and γ-ray discrimination. In the experiment, the efficiency of two different thickness of polyethylene sheets as a recoiled proton emitter and the effectiveness of Teflon sheet as a recoiled proton separator between two pieces of imaging plates were confirmed. The experimental results showed.that Teflon sheet worked well and the method could be applicable to fast neutron radiography with effective γ-ray discrimination.

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A method to measure void fraction quantitatively by neutron radiography was proposed. The method to measure the offset of the image by the brightness of the umbrer made by a neutron absorber tape placed between the neutron source and the object have already been proposed. The quatitative brightness was calculated by subtracting the image with the tape from the image without the tape. The quatitative brightness on one image line could be obtainable with this method. A simple algorism for estimating the offset by interpolation by the two or four umbrers in one image with neutron absorber grid.

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Visualization and void fraction measurement are important to study the behaviors of a two-phase flow. It is often difficult to visualize two-phase flows and to measure void fraction distributions in complicated conduits like a rod bundle. In this study, visualization of two-phase flow in a rodbundle near the spacer were carried out and the void fraction distributions were measured by using neutron radiography system in Japan Atomic Energy Research Institute. Quantitative void fraction distributions in a rod bundle were presented.

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The refrigerant two-phase flows in a distributor and a simulated plate heat exchanger with a single passage used in a compression-type refrigerator were visualized by real-time neutron radiography. For a distributor, the liquid fraction in the each tube was measured by some image processing method. On the other hand, for a plate heat exchanger, the two-dimensional distribution of void fraction was measured quantitatively by the umbra method. As a result, it was shown that the dynamic behaviors of refrigerant at the inlet of the section strongly affected on the performance, that is, a distribution performance of a distributor and a liquid distribution in a plate heat exchanger.

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In a core melt accident of a fast breeder reactor, a possibility of re-criticality is anticipated in the molten fuel-steel mixture pool. One of the mechanisms to suppress the re-criticality is the boiling of steel in the molten fuel-steel mixture pool because of the negative void reactivity effect. To evaluate the reactivity change due to boiling, it is necessary to know the characteristics of gas-liquid two-phase flow in the molten fuel-steel mixture pool. For this purpose, boiling bubbles in a molten fuel-steel mixture pool were simulated by adiabatic gas bubbles in a liquid metal pool to study the basic characteristics of gas-liquid metal two-phase mixture. Visualization of the two-phase mixture and measurements of liquid phase velocity and void fraction were conducted by using neutron radiography and image processing techniques. From these measurements, the basic characteristics of gas-liquid metal two-phase mixture were clarified.

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Flow visualization of bed-materials in a fluidized bed was conducted using neutron radiography. The silica sand of the bed-materials are almost transparent for the neutron beam. To have a clear contrast of the visualized image, small amount of sand coated by cadmium sulfate was mixed into the bed-materials. Image processing technique was successfully applied to these images to obtain quantitative data of void fraction distribution.

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Fluidized-beds are important equipments in many industrial systems, such as chemical reactors, coal and/or incineration firing systems. Bed-material movement in the fluidized-bed has a prime important in the heat transfer process. The fluidized-bed installed vertical-tubes was visualized by X-ray radiography system. Image processing technique has been developed to measure quantitative data of void fraction by X-ray radiography. The visualized images clearly showed an interaction between rising bubbles and tubes.

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X-ray microscopy is promised to be a useful tool for studying living biological specimen without dehydration and fixation. A laboratory-sized x-ray microscopy system was realized as a flash contact microscopy using a laser-produced plasma as a flash x-ray source. X-ray images of living biological specimens obtained by the system were provided. Some of these images indicate fragile structures in living states, which are damaged by dehydration of specimens.

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Three-dimensional tomographic imaging using x-ray phase information is reported. The contrast in normal x-ray transmission images is generated by the difference in x-ray absorption. Therefore, structures in weakly x-ray absorbing objects are hardly depicted. Because the interaction cross section of x-ray phase shift is about a thousand times larger than that of absorption for low-Z elements, highly sensitive imaging is achieved by detecting the x-ray phase shift. We used an x-ray interferometer to measure interference patterns and phase-shifting interferometry to obtain x-ray phase maps from the interference patterns. Phase-contrast x-ray CT reconstructs three-dimensional images from the x-ray phase maps. This paper introduces the principle of this technique and observation results obtained for cancerous tissues using synchrotron radiation.

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We have developed a new flat panel detector (FPD), known as LANMIT (Large Area New MIS sensor & TFT). This sensor in based on a thin film transistor (TFT) / metal insulator semiconductor (MIS) photoelectric converter array made using hydrogenerated amorphous silicon (a-Si). The sensor consists of 2688 * 2688 pixels with a pitch of 160 μm, giving an active imaging area of 17inch*17inch (43cm * 43cm). Optical photons generated by x-ray interactions with scintillator coating are detected by the MIS-type photoelectric converters, and the resulting signal is read out by switching the TFTs. LANMIT benefits from a very low level of noise, and a dynamic range which covers most of the exposure range used in radiology. Resolution (MTF) is appropriate for digital chest radiology, and the detector provides good contrast x-ray images. The simple fabrication process of this sensor promises high productivity and therefore a low cost flat panel detector.

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A high energy industrial X-ray computed tomography system using silicon semiconductor detectors (Si-SSD) and electron linear accelerator (LINAC) was developed to obtain high resolution 3D images of high density and large scale object. To increase photon sensitivity, detector elements were placed parallel to the X-ray beams. The obtained sensitivity of 20% for X-ray of 3MeV was 3×10⁴ times higher than that of X-ray films. It was clarified that the photon sensitivity of X-ray detectors restricts the performance of high energy X-ray CT, and it is shown that a CT image of 200mm thick iron object can be obtained with 0.2mm space resolution.

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This paper presents the visualization of flow boiling in a circular tube under swirl flow by the Real Time Neutron Radiography (RTNR) and the ultra-fast X-ray computed tomography scanner (XCT). The twisted tape inserted in the tube generates the swirl flow. The swirl flow affects the void distribution in boiling flow and heat transfer phenomena. RTNR gives the void distribution in the plane orthogonal to the test section. And, the ultra-fast XCT can measure the instantaneous cross sectional void distribution. The combination of RTNR and ultra-fast XCT can be used to determine in-situ three-dimensional void distribution in complex geometry such as swirl flow boiling. XCT experiments were preformed using Freon 123 as working fluid. RTNR experiments were conducted using Freon 134a at conditions similar to the XCT experiments. The visualization results show that liquid is forced to the heated walls and tape insert in each sub-channel. The understanding of these void distribution characteristics may lead to increased knowledge of the flow boiling mechanisms.

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Multi-dimensional interface structure in air-water two-phase flow was visualized by using a fast X-ray CT scanner, which is able to scan a cross section approximately 100 times faster than conventional systems. To simulate flow channels in heat exchangers, locations and pitches of 3 rods were varied in a vertical tube. Gas-phase distribution in the cross section was reconstructed for analysis of the void fraction and the interface area concentration. The same facility was then used to visualize the water jet interface while penetrating through a Fluorinart pool. Due to relatively large density difference between the two immiscible fluids (1.7), the deformed interface structure was successfully detected. For visualization of overall jet interface, the jet nozzle was lifted upward at a constant velocity while scanning the cross section. In both two-phase flow and water jet interface visualizations, quantitative measurements of the phase distribution and the interface area concentration were made from reconstructed cross section images.

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