Advanced Materials Research Vols. 243-249

Abstract: Ignoring the influence of the load sequence and the damage caused under low-stress level are two mail shortcomings of traditional fatigue life estimation method based on the Miner theory. Fuzzy method for fatigue analysis of the foundation of offshore wind turbine is investigated. A fuzzy accumulative damage model is founded and used for fatigue life analysis of a tripod foundation. The fatigue damage is calculated using the traditional certainty method and the present fuzzy method. A tripod foundation under single-level and multi-level fatigue loads is used as the test structure. And the load sequence is considered. The calculation results of stress level are used with three forms, named the increasing mode, the to-and-fro mode and the sine mode, for structure fatigue life analysis. It reveals that the load sequence and low-stress level play an important part in the fatigue analysis and should not be ignored. The anti-fatigue character of the structure under a group of increasing loads is better than the structure under a group of decreasing loads; and it is called the forging effect. The present fuzzy accumulative damage model is more accurate and reasonable than the traditional certainty method.

Abstract: Mechanism of sulfate attack is a very complicated process. In the laboratory, there are a variety of testing methods for cement resistance to sulfate attack. But there are still some problems. For example, the method often used in the United States Association standards and testing (ASTM) does indicate that expansion happens in the event of specimens’ breakage, but not point clearly the minimum amount of expansion leading to the strength damaged. In the present study, the method of measuring expansion of hardened cement paste sulfate resistance is discussed. It is found that experimental measurements can be used to study the erosion of sodium sulfate solution, but not be used to evaluate the anti-corrosion properties of hardened cement paste to magnesium sulfate.

Abstract: A structure was designed to reduce the large forces exerted by level ice on offshore structures in shallow icy waters, by breaking the large ice floes into small pieces from flexing-induced failure. A series of model tests was conducted to simulate ice loads on the structure. A concrete model of it was adopted to verify the stability of the structure under the action of ice floes, which had five different thicknesses. The results show that ice forces on the structure are low and that the stability of the structure under different sea bed is good.

Abstract: The effect of the common cations, anions and humic acid on the reduction of NDMA with zinc(0) was investigated. The NDMA removals were not the influenced greatly by the cations. All the anions depressed the NDMA final removal in the order of SO₄^2-＜Cl^-＜HCO₃^-=NO₃^-＜S^2-. The humic acid of the varied concentrations inhibited the NDMA final removal. The initial NDMA removals were enhanced by several ions and the humic acid. The enhancements could be due to the promotion of the passive film breakage, the generation of reactive sites or the inhibition of the passive film formation. The final removal decrease may be caused by the diminishing reactive sites or the competing effects from the ions.

Abstract: In order to realize the automatic energy saving control for centralized hot water supplying system, this paper puts forward a frequency conversion adjusting speed automatic supplement water system with frequency converter used as driving unit pump. It can provide constant supplying hot water pressure by timely adjusting supplement water quantity according to the change of water consumption. The hot water temperature control system was designed to maintain the temperature constant through throttle governing steam quantity. Through the practical run, the whole system works steady, which has remarkable energy-saving effect and high automatic degree.

Abstract: Conbined with the Eco-residential Island, the project of reclaimed water utilization for Liaobin water town in Panjin is mainly introduced. The reclaimed water resource contains rainwater and domestic sewage water, which is collected mainly in the range of urban (regional).After the second-level processing by sewage treatment plant, it is mainly served as flushing water ,which is called “full-sewage” reuse system; in dry season, it is reused directly after corresponding treatment; and in rainy season, the excessive water is pumpinged into the surrounding waterbodies. The research analysis indicates that the plan of “full-sewage” reuse system and the seasonal reclaimed water utilization system used in this area are reasonable and feasible, which can make full use of the reclaimed water and save the water resources effectively, meeting the demand of sustainable development .

Abstract: Based on the theory of sustainable regional water resources, the basis theory of comprehensive evaluation about the beneficial cycle of urban water use was constructed and the evaluation index system about the beneficial cycle of urban water use was established. Using the improved AHP to comprehensive assessment water using conditions of Nanchang City, the evaluation result is middle. So we must analyze the reasons and the main factors of the evaluation results for better water utilization in Nanchang City.

Abstract: In order to run the secondary pressurizing pump station in the residence community more economically, the operating principles, control methods and suit conditions of four kinds of water supply systems were introduced and they are: common circular soft started constant pressure frequency-changing system, circular soft started constant pressure frequency-changing system with little capacity pumps, high efficiency frequency-changing system within full flow area and variable flow and pressure system. The energy efficiencies of these kinds of water supply systems were analyzed with their engineering applications. The issues to be concerned in these water supply systems were also discussed.

Abstract: By distributing influent to different action zones, a high sludge concentration and high sludge concentration gradient were carried out in ECOSUNIDE treatment system. Carbon source was respectively supplied to anaerobic and anoxic tanks, meeting the demand of PAOs for phosphorus release and denirifiers for denitrification. The operation mode of muliple A/O (anoxic/oxic) was employed to avoid the inhibition of nitrate on nitrification and phosphorus accumulation, improving the nutrient removal efficiency without internal reflux. In the paper, the experiments were performed on ECOSUNIDE to investigate the change law of water qualities in the whole system by monitoring MLSS and every index including COD_Cr, ammonia nitrogen, total nitrogen and total phosphorous, etc. From the results, the removal rates of COD_Cr, ammonia nitrogen, total nitrogen and total phosphorous were 87.28%, 96.99%, 77.97% and 79.92% reseparately and there was a consistency of the removal rule for every kind of pollutant in the system.

Abstract: The PVDF ultrafiltration membrane was modified by step in situ polymerization coupled with TiO₂-PANI membrane surface modifying. It has been prepared by different oxidants, such as ammonium persulfate (APS) and ferric chloride (FeCl₃). Meanwhile, application of the modified PVDF ultrafiltration membrane on treating micro-polluted surface water was studied. Turbidity removal efficiency, organic compounds and ammonia nitrogen (NH₃-N) were mainly concerned. The results show that the modified PVDF UF membranes can remove 95% turbidity, UV₂₅₄ higher than 50% which was increased greater than the original film. When FeCl₃ was taken as oxidant with 0.03mol/L, less by-product, NH₄⁺, was generated than APS. Thus, the ammonia nitrogen removal rate is as high as 85.2% and is 20% more than the original film.