We have studied the criteria of the ratio of zinc area to that of the steel to cease the corrosion of steel in flowing tap water. The protection potentials and currents for corroded and non-corroded steel. The ratio of zinc area to that of steel enough to prevents corrosion is about 1/3 for non-corroded steel. The protection potential was -450mV.vs. SHE (Standard Hydrogen Electrode). The protection current was about 0.60A/m^2 in the early stage, while it reduced to 0.12A/m^2 in the steady state. On the other hand, when the steel surface had been corroded before testing, the ratio mentioned above is 15 times larger than that of the previous case. The protection potential is -620mV which is close to the theoretical value by M. Pourbaix. The protection current was 0.75A/m^2 in the early stage, whereas it varies widely in the steady state.

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This paper describes the three-dimensional numerical simulation of radiative heat transfer from pavement and gases which exist in urban street canyon space to human scale object with consideration of absorption and emission process of the participating non-gray gas mixtures consist of H_2O and CO_2. The ambient temperature and the participating gas concentration were assumed to be of the present summer condition (Case A: ambient temperature 35℃, relative humidity 66%, CO_2 concentration 400ppm) and the projected extreme condition ca 2100 (Case B: 40C, 66%, 800ppm). Effects of solar radiation were not considered in the simulation. The results demonstrated that the gas radiation significantly affects the infrared radiation flux to human scale object from the pavement and from the participating gas mixtures especially in case that horizontal and vertical scale is lager than 20m. Radiation flux with participating gas mixtures is approximately 120〜160W/m^2 higher than that without participating gas. A half of total radiation flux into human scale object model comes from the participating gas mixtures. Participating gas mixtures absorb approximately 30% of total incident radiation flux from the pavement to human object scale model. These results indicate that non-gray gas mixtures could play an important role in the human thermal comfort in urban outdoor environment in hot and humid summer condition. The simulation result under the projected 2100 condition (Case B) is almost same as the result under the present condition (Case A). This means that CO_2 concentration does not affect to radiation transfer to human scale body at least within the scale treated in this study. Furthermore, it is shown that the bottom part of human scale object model tends to receive the radiation from the pavement, whereas the top part of the model mainly receives the radiation from the participating gas mixtures.

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This study aims at the development of software that recognizes pipe size and length from architectural 2D-CAD drawing automatically. The relation of the character data that shows pipe size and the line data that shows the pipe in CAD data is recognized automatically. As a result, the pipe length of each size that considers the connection of the pipe can be measured. The system including proposed algorithm was tested by using the real business data, and shows the recognition rate that be able to be used in business.

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This research studied the performance of a fast calculation method of direct solar radiation using computer graphics (CG) technique. This method uses the parallel projection images drawn with the CG technique to calculate the amount of direct solar radiation incidence on surface elements that are necessary in CFD heat transfer problems. This research described the principle of the proposed method and concrete procedure to apply the method to CFD calculation of indoor environment. In this method, the refined algorithm developed in the field of CG to search surfaces that direct solar radiation comes in, is automatically applied. Further, the surfaces can be calculated at high speed by using graphics hardware. It was found that the accuracy of this method was within the acceptable limit. As a result, it was verified that this method has a possibility to become an effective tool for the analysis of heat transfer problems with solar radiation.

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In this thesis, we analyzed used antifreeze in terms of corrosion protection. The antifreeze was typical in hot water heating system at domestic general houses. Secondly, we investigated the possibility of pitting corrosion on carbon steel in the used antifreeze and the same kind of pre-use antifreeze by electrochemical measurements. We also studied on the overall corrosion rate in these solutions. The concentration of the principal component in the used antifreeze was lower than the setup concentration. The residual ratio of inhibitors in the used antifreeze decreased as time passed. Therefore, we concluded that the concentration of the correspondent inhibitors reduced. The possibility of the pitting corrosion on carbon steel in the used antifreeze was higher than in the pre-use antifreeze because not only the dissolved oxygen survived, but also the dynamic potential of the pitting corrosion on carbon steel lowered. Moreover, the used antifreeze adequately inhibited the overall corrosion for 5 or 6 years.

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