Ultrasonic cavitations can control algal growth. Considering water ecosystem protection and characteristics of ultrasonic technology, low frequency and low power ultrasonic was especially suitable to control algal growth in water bodies. Effects of low-frequency and low-power ultrasonic irradiation on natural blend algal growth were investigated. The algae spices were collected from a fresh water body. It mainly consists of Cyanophyta, Bacillariophyta and Chlorophyta. The results showed that ultrasonic irradiation with frequency of 60KHz, power of 0.24W/cm2 and irradiation time of 1min, inhibited algal growth significantly. Inhibition of ultrasonic irradiation on algal growth enhanced with ultrasonic power increased. Inhibition did not increase again When ultrasonic power exceeds 0.24W/cm2. The effect of algal control was sustainable by ultrasonic irradiation with interval period of 2-4 days.
The jointed finite element method (JFEM) is used to analyze the deformation and failure characteristic of fractured rock mass and anchor reinforcement effect for the water collection shaft of the main power house of Dagangshan Hydropower Station. The results show that the JFEM not only simulates the actual rock mass structure very well, but also gives the reasonable simulation results for the common unstable rock mass. The JFEM may accurately simulate the major deformation characteristic and collapse mechanism, which is another effective way to analyze the stability of fractured rock mass. The on-site monitoring results show that the anchor reinforcement is effective for the water collection shaft
Phosphorus limitation on bacterial regrowth was studied in source water, water treatment process and water distribution system of J Water Supply Plant in T city, by modified AOC method and MAP analysis. Based on the study, the follows can be concluded: ① MAP(Microbially Available Phosphorus) concentration was higher in source water and water treatment process, which was 5~38µg PO43--P/L. However in water distribution, MAP concentration was lower, which was less than 5µg PO43--P/L. ②Coagulation and sedimentation can remove MAP efficiently. 31%~68% of MAP can be removed in these process. ③ In source water and water treatment process, there was no evident difference between AOCpotential, AOCp and AOCnative. So assimilable organic carbon (AOC) was the most important factor of bacterial regrowth. In water distribution system, the concentration of AOCpotential and AOCp were 2~8.7 times of the concentration of AOCnative. So phosphorus limited bacterial regrowth.
The constitutive relation of concrete under uniaxial tension and compression is an essential theoretical basis for structural analysis of concrete. Because of the lack of sufficient stiffness for ordinary test device, a stable decline branch of stress-strain curve could not be obtained. The condition of realizing the stress-strain complete curve for concrete uniaxial tension and compression is derived. The experiment device for uniaxial tension and compression was designed and fabricated with increasing stiffness method. Experiments were carried out for concrete with grade C30~C60 and strain rate 10-5/s~10-2/s. The equation for stress-strain curve in the rising branch were obtained and so were the complete stress-strain curve of uniaxial tension and compression under different strain ratio, which provide the theoretical basis for concrete structural analysis.
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