This paper derives a precise form of the relationship between facility density and population density from the general assumption that facilities locations are determined in such a way as to minimize the travel distance of users. Models generally lead to an exponential function with an exponent, and especially, the 'minisum' standard derives that facility density is proportional to population density raised to the two-thirds power. After the application of this theoretical relationship to empirical relations, it is found that some public facilities confirm the result. The exponent of public facilities tends to be smaller than that of retail stores.
Recently, huge amount of waste has been recycled in cement plant, and many kinds of aversive substances (chlorides, alkalies, sulfates and heavy metal salt) have been brought into cement manufacturing process with the wastes as raw materials. These substances are usually removed by chlorine bypass system from cement kiln-preheater, called as “K powder”. Since cement plant is expected to use more wastes, “K powder” constituents should be separated with each other as recycled resources.In this study, we tried sulfidized flotation to separate lead components from “K powder” with the recovery of more than 60% by optimizing the flotation conditions, and clarify the reaction mechanism. As a result, we found the optimum conditions in case of 150 g/L pulp density of “K powder” as follows. 1) Adjust the initial pH of the pulp to 3.0 by sulfuric acid, 2) Take 30 min for aging of gypsum formation at the pH 3.0, 3) Add the NaHS of 20 g/kg-“K powder” and take 15 min for sulfidization, 4) Add the PAX of 3.2 g/kg-“K powder” and take 15 min for conditioning, 5) Readjust the pH to 3.0∼4.0 by sulfuric acid and carry out flotation. We also found that the formation of K2Pb(SO4)2 during the conditioning causes the decrease of lead recovery in flotation and that the K2Pb(SO4)2 formation can be suppressed by limiting K+ concentration in solution under 800 mmol/L and/or keeping the pulp temperature over 40°C at the stage of NaHS addition. Then, we could separate lead components from “K powder” with the recovery of 60 % as a lead concentration of 10∼30 Pb wt% under the same condition of sulfidized flotation for the “K powders” of various component.
The dependence of sea-surface microwave emissive prop erties on wind speed, frequency, incidence angle, and polarization arn discussed in detail, in terms of wind-speed sensitivity of the brightnes temperature (defined as a change in brightness temperature with a un, change in wind speed) to the last three observational conditions, ovet the frequency range from 1 to 40 GHz, comparing our results at 6.7 and 18.6 GHz with many investigators' results at various levels from surface to satellite. This wind-speed sensitivity shows marked incidence angle and polarization dependencies. In vertical polarization, a wind-induced increase in the brightness temperature decreases with incidence angle. Then, the vertically polarized brightness temperature of the roughened sea surface is equal to that of the calm surface at an incidence angle between 50 ° and 600, and is higher below, and lower above, this angle; in other words, the above sensitivity is higher and takes a positive value at lower incidence angle and it is lower and takes negative value at higher incidence angle, with a wind-speed-insensitive angle existing between 500 and 600. A wind-induced change in the horizontally polarized brightness temperature shows no marked incidence angle dependence, but a uniform increase over the incidence angle. Both polarizations do not essentially change their characteristics in the above dependencies but gain wind-speed sensitivity with frequency; however, the horizontal polarization is much more sensitive to wind speed than the vertical one over the entire incidence and frequency ranges.
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