A new type laser instrument for measuring the size of raindrop, called a laser raindrop gauge hereafter, is developed. This gauge can measure the minutely rainfall intensity besides the raindrop size distribution. The observation has been carried out at the campus of Chuo university in Tokyo for two years. It is concluded that the relationship between the radar reflectivity factor and the rainfall intensity can be treated as approximately constant during a rainfall event. If the radar parameters, B and β for a rainfall event are decided by the laser raindrop gauge, the rainfall intensity with radar raingauge can be estimated more accurate than by the conventional methods proposed formarly.

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This study analyze cold air flow which causes convergence of band cloud in winter season by using the stratified flow model with two layers. It was found from our observation using a kite baloon that the cold air flow has the structure of two layers to be similar to a stratified flow like salt water flow. Extended distance and the profile of cold air flow were predicted by the numerical model with considering the thermal effect from Ishikari Bay. The results of the model applying to the Ishikari Bay area showed wind field estimated with a doppler radar near the bay. Stavility analysis for the stratification of cold air flow was also intended to be found that the Kelvin-Helmholz instability should not effect the stability of the cold air flow.

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A spectral response function is derived based on a vibration equation on flexible plants. Measured spectrum on turbulence in flow over flexible plants is used to calculate the vibration spectrum of plants. It is found that the vibration of flexible plants has two peaks corresponding to resonant vibration of each plant and honami. The predicted profile of spectrum for plant vibration agrees very well with the result of wind tunnel tests. It is concluded that the honami is induced by organized vortices generated by a shear instability of flow.

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On making accurately and effectively a numerical diffusion simulation, one should pay much attention to both the computational scheme for calculating the advection term and the computational grid size. The usable schemes for obtaining the highly-accurate results depend on not only computational conditions such as grid intervals on time and space but also hydraulic conditions such as phyical diffusion and velocity, while there will be the most effective grid size to get an accurate solution within the allowable margin of error if the scheme used for the numerical simulation is chosen. We have attempted to develop a criterion for selecting the most usable scheme to calculate the advection term and deciding the most effective computational grid size. We made a 2nd order numerical diffusion term represent the truncation error terms, which is a infinite series. The criterion was made up by utilizing the 2nd order numerical diffusivity. Some one-dimensional test diffusion simulations have been carried out to inspect the validity of the criterion.

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Surface waves in the rapids of the river show the complicated patterns which are influenced by the bottom topography. Two-dimensional shallow water equations with dispersion terms are used to discuss the instability of steady nonuiform flows over sinusoidal bed. Floquet's theory shows that quasi-periodic eigenfunctions with respect to spacial variables can be introduced to solve the equation for an infinitesimal disturbance. Here, two physically important spatial patterns, such as Peak-valley structure and Staggered pattern, are investigated and their unstable regions are plotted in the phase plane of Froude number and the wavenumber of the bottom surface. Furthermore, the frequency of the waves observed at the waterside in the rapids will be discussed.

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Turbulent flow characteristics of open channel flows in a rectangular trench are analyzed by the particle image velocimetry (PIV) and the large eddy simulation (LES). The effects of the depth of the trench and the Froude number are discussed in detail. The results for the lower Froude number show a favorable agreement between PIV and LES except near the free surface. It is suggested that the separated shear layer has an organized structure composed of longitudinal vortices. The effect of Froude number is clearly indicated by using the convection diagrams showing the space-time variations of the velocity field.

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In compound open-channel flows, it is very important to clarify the interaction between main-channel and floodplain induced by coherent vortices, so-called secondary currents, etc. In this paper, a new quantitative visualization technique called the "Particle-Tracking Velocimetry (PTV)" was used to investigate space-time correlation structures of coherent vortices because instantaneous velocity components can be obtained at all grid points of laser-light-sheet (LLS) from continuous four images of one particle (four-field-images'method). At that time, a new-type two-component fiber-optic laser Doppler anemometer (FLDA) was used to verify the accuracy of PTV measurements.

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A particle tracking velocimetry (PTV) system has been developed to obtain instantaneous two velocity components on several sections in three-dimensional space. The flow visualization is conducted by means of parallel laser-light sheets created by a scanning laser beam and the visualized particle images are taken by a high-speed video system synchronized with the scanning. In order to obtain higher accuracy in velocity measurements than usual PTV, some improvements are made on the analyzing procedures: the extraction of particle images, the determination of their center points, the derivation of velocity components and others. The present PTV was applied to the transient flows in a cylindrical tank with a rotating disc. As a result, two-dimensional transient flow patterns with large scale disturbances are continuously captured in three-dimensional space.

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Experimental study was carried out to develop the settlement and dispersion process of ocean dumped mud. Based on this experiment, a physical model was proposed for predicting the turbidity that will produced by ocean dumping. Then, the validity of the model was confirmed by comparing with the field experiment.

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A new predictive model of contourline change is developed, in which longshore sand transport formula and continuity equation of sand are solved numerically in each sublayer of the beach divided vertically. Modeling procedure of beach changes not only on the natural sandy beach but also in the vicinity of sea wall, groin, offshore breakwater, submarine canyon (dredged hole) is proposed. In each case model movable bed experiment is carried out to verify the effectiveness of the model. Good agreement between experimental results and numerical simulation is shown. This model has an advantage that it can predict formation of beach scarp due to dune erosion and sand dischange into a submarine canyon or an offshore dredged hole compared with the oneline (shoreline) model of beach changes.

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A new set of mild-slope equations, taking into account of evanescent modes, is derived for the analyses of wave-diffraction and radiation by a floating body in a harbor. A Galerkin-type finite element method is applied to the numerical modeling. In this model, the fluid motion in the whole harbor domain is represented in vertically integrated forms. This acheives much higher computational efficiency as compared to conventional “partially three-dimensional” models. The results of fundamental examinations indicate importance of evanescent modes in predicting hydrodynamic forces and sufficient reliability of the present model. Comparison with a conventional numerical model shows significant improvements in computational efficiency.

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Recently, Life-Cycle Assessment (LCA) has been attracting people's attention who have been concerned in the global environmental problems as an method that can assess the environmental impacts of materials, products, several social services and so on. LCA is a tool to evaluate the environmental impacts of a product or activity, across its entire life. But the conventional LCA can not asses the effect of use of recyclable materials into the products adequately. A purpose of this study is to propose a new evaluation method of the process of recycle. The new evaluation method assess the environmental impact of the following three processes; a) Process of waste disintegration, waste incineration and final waste disposal, b) Process of a product manufacturing from natural resources, c) Process of re-manufacturing a product from recycled materials. An effect of the recycle of an electric washing machine on the reducing environmental impacts is evaluated with our evaluation method. It became clear that if we use the new evaluation method, we evaluate reducing the environmental impact by recycle more adequately than before.

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A field observation was performed in an urban canyon for heat balance and micro-climate. It was found that the wind velocity is retarded by the buildings, and the temperature and the humidity are increased in the urban canyon compared with the outer atmosphere. The heat balance indicates that sensible heat, H, and the heat flux toward the building, G, are dominant at the building roof. In the urban canyon, the latent heat, lE, is comparable with H and G, if plants locate in the canyon road.

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Several innovative anaerobic digestion (AD) technologies have been developed during the last two decades. It is necessary to overcome a number of barriers before an innovative AD technology is commercially available for the benefit of potential users. Activities related to commercialization of a two-phase anaerobic digestion (TPAD) technology for gasification of solid feeds are described.

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