Katsuhito Yamaguchi

The influence of urban canopy configuration on urban albedo

We propose a calculation method for shortwave radiation flux and longwave radiation flux within the urban canopy and investigate the influence of urban canopy configuration on net radiation flux. In the assumed urban configuration, buildings of equal size are arranged in a regular lattice within the urban canopy. The net shortwave radiation flux and longwave radiation flux within the urban canopy were calculated by the photon tracking method based on the Monte Carlo method. The albedo value obtained by this method shows close agreement with experimental data, and the average sky view factor shows almost perfect agreement with the theoretical value. Moreover, we calculated the urban albedo for the urban canopy configuration including roads and building height distribution.%Moreover, we calculated net radiation within the urban canopy in %consideration of roads and building height distribution.We found that the sky view factor of the ground surface is high when building coverage is low, building height is low, open space by roads exists, and building height is non-uniform. Moreover, we found that the albedo value is high when building height is small, open space by roads is wide, and building height is uniform. The albedo value was found to vary in a complicated manner with change in building coverage.

Development of an automatic system for counting asbestos fibers using image processing

ABSTRACT Atmospheric concentrations of carcinogenic asbestos fibers, have traditionally been measured visually using phase contrast microscopy. However, because this measurement method requires great skill, and has poor reproducibility and objectivity, the development of automatic counting methods has been long anticipated. We have developed the Asbestos Fibers Automatic Counting System (AFACS), and verified its accuracy via application to illustrations obtained from the Asbestos Internationa) Association (AIA). Important features of the AFACS system are as follows: (1) Counting criteria of the automatic counting system conform to those of visual counting (2) The cost of the whole system is low because it is microcomputer-based.

Simulation of climatic effects by construction of reclaimed island in Pusan, Korea

Abstract A project is now underway on the construction of a reclaimed island in Pusan city, Korea. The reclaimed island is to be constructed on the sea between Yeung-do and Songdo district in Pusan area and is about 6.2 km 2 A part of the needed soil for the reclamation is supplied by cutting down the top of hills in Yeung-do and Songdo. So we predicted the local climate effects, such as the wind and the air temperature distributions, that would result because of those large-scale modifications of the earth surface. For the area around the reclaimed island the three-dimensional numerical model which employed the nested technique to calculate with the higher resolution was used to predict the climate effects. The nested technique uses two grid systems, one for large-scale calculating region which is the coarse mesh grid (CMG) and the other for small-scale region which is the fine mesh grid (FMG). The simulations were carried out both for the present situation and for the condition that could result after construction of the reclaimed island on the typical summer day when the sea and land breezes strongly developed. The first calculation results reasonably agreed with the observed data. And the second calculation results indicated the following: (1) the temperature would increase about 1°C above the reclaimed island at the daytime, (2) the temperature would slightly decrease above the reclaimed island but increase about 0.5 °C above the top of both hills which are cut down at the nighttime, (3) the wind velocity would increase on the west side of the reclaimed island at the daytime, (4) the wind velocity would decrease above the reclaimed island but increase above the top of both hills cut down at the nighttime.

Application of a Fast Algorithm for Pattern Tracking on Airflow Measurements

A fast algorithm avoiding the calculation of correlation coefficients is applied to the pattern tracking for an airflow measurement. The pattern similarity is defined by the reputation number of the summations of gray level difference between corresponding pixels until the accumulation exceeds a critical value. An example of the sensitivity examination of parameters included are also described.

A comparative study of the Mellor–Yamada and k–ε two-equation turbulence models in atmospheric application

The present study systematically compares the Mellor–Yamada (MY) model and the k−e algebraic stress model in order to verify the possibility of using the k−e algebraic stress model in atmospheric applications. The results of the parameterization process and atmospheric application of both models confirmed that the MY model neglected the pressure redistribution effect of buoyancy due to 〈uiuj〉 and 〈uiθ〉 and that of shear due to 〈uiθ〉. In addition, the MY model overestimated the turbulent energy dissipation. Based on the formulation of the k−e algebraic stress model, we modified the constant value Cμ(=0.09) in the standard k−e model to obtain the variables CμM and CμH to account for atmospheric stability. Finally, the results of the simulation obtained from the Wangara experiment verify the possibility of using the k−e algebraic stress model in atmospheric application.

Three-Dimensional Concentration Measurement in a Ventilated Room Model Through Digital Image Processing

A method to measure a 3-D concentration distribution of tracer particles in the airflow through visualization and digital image processing is presented. The tracer particle images obtained in different depths illuminated with a laser light sheet are analyzed synthetically including the effect of ray extinction due to light scattering.

The Numerical Prediction of the Micro Climate Change by a Residential Development Region

We developed a numerical model that considered the influences on the thermal environment of vegetation, water surfaces and buildings to predict micro climatic changes in a few scales; and applied this model to the Mino residential development region in Osaka Prefecture by using a nested technique. The calculated temperatures and winds in the residential development region reasonably agreed with the observed ones. We then investigated the influences on the thermal environment of the construction of a dam, the change of the green coverage rate. The results obtained from the numerical simulations were qualitatively reasonable.

Prediction of Soil Acidification Using a Dymanic Model at a Bamboo Forest in Osaka Prefecture

This study is based on research of throughfall formation and soil chemistry processes. Through the experimental verification of the cation exchange part of the simulation model; making use of results of the flux of acid deposition on the forest and the chemical weathering of soil mineral, we predicted the future soil acidification. The result indicated that chemical weathering occupies the important portion of acid neutralization capacity of the soil and that significant soil acidification will not occur in this field within 40 years, even if the present acid load continues in the future.

Examination of the Availability of the Cloud Drift Vectors Obtained from the Cloud Pictures of the GMS for Estimating the Large-scale Wind Field

Now, the acid rain has become one of the environmental problems of global scales. In many cases, the cause substances of the acid rain are transported through a long distance. Therefore, the acid rain is not considered as domestic problems only. The long distance transportation model has been developed as one technique for solving the long distance transportation problems of the cause substances of such acidifying. In this model, presumption of a wind field is the most important factor.In order to apply this model to the East Asia area, we tried the presumption of the wind field using the cloud picture obtained from the GMS (Geostational Meteorological Satellite, Himawari by name.) We verified the accuracy of this wind field presumption technique by comparing mutually between the presumed technique of this wind field, the wind vector obtained by the Meteorological Agency Japan, upper-layers weather data, and the GPV (Grid Point Value) data.

3-D Airflow Measurement Using Smoke Particles

A new 3-D PIV-technique that is applicable to low velocity airflow in a real space such as indoor airflow is proposed, and its performance is inspected through a simulation and an experimental application. In this technique, two parallel planes separated by short distance are illuminated by a pair of laser light sheets of different colors. The visualized images are separated with optical filters, and recorded on VTRs. The 2-D tracer pattern movement on visualized planes is tracked with pattern tracking and the movement normal to the visualized planes is calculated from the difference of tracer concentration between two planes. The simulation result showed that the algorithm proposed here can calculate 3-D velocity field adequately, but the experimental result showed that the luminous intensity difference between two visualized planes became the main source of experimental errors.