Advanced Materials Research Vols. 433-440

Abstract: Processing waste water of heavy metals by biosorption-flotation was effected by many factors. Existing coexisting ions in waste water is a important factor. The influence of coexisting alkaline-earth metals ions and heavy metals ions of Cd ²⁺, Cu ²⁺, Hg ²⁺, Zn ²⁺, As ³⁺, on results of adsorbing and floating Pb2+ in waste water was examined by using Gordona amarae as adsorbent and laurylamine as collector. The results showed that different sort of heavy metals ions and alkaline-earth metals ions have different influences on biosorption-flotation. The influences on biosorption-flotation by coexisting ions showed that ions exchange mechanism, surface complexation mechanism, oxidation-deoxidize and inorganic micro precipitation mechanism exist probably

Abstract: A one-dimensional mathematical model of mass transfer during CO2 gas hydrate film formation at the boundary between the gas and water is established by analyzing the process of the static system. According to the model, we can get the concentration distribution of free CO2 in the hydrate film along with the time, and the conversion rate of hydrate with time can also be obtained. The results calculated at specific experiment condition in the system are analyzed. It indicates that the conversion rate can reach about 85% after 10 hours under static condition with 3.5MPa pressure and 0.5°C temperature by pure water when the initial reaction liquid depth is 20 mm

Abstract: The objective of this paper is to analyze the enhancement mechanism of ammonia bubble absorption performance by nanofluid. In this paper, the process of ammonia bubble absorption is divided into three different steps: the bubble growing, the gas absorption in liquid phase and the interface phase transfer. According to the analysis, nanofluid can enhance the diffusion coefficient or the absorption performance in each step, and enhance the whole absorption performance resultly; the gas mass transfer during the bubble growing is enhanced by nanofluid for the surface tension decrease; the main cause for the enhancement of the gas absorption in liquid phase is considered as the transport effect of nanoparticles carrying ammonia gas molecule and the vortex transfer effect arising from Brownian motion of nanoparticles; the main cause for the enhancement of the transfer at phase interface is considered as the Marangoni convection and the vortex transfer effect due to nanoparticles.

Abstract: In this paper, by the large scale model test of pile-soil in remodeling loess foundation, authors research the basic discipline of pile-soil interaction plastic hysteretic property of pile foundation in loess area under horizontal cyclic load and obtain hysteretic curves, skeleton curves and relationship between equivalent viscous damping coefficient and displacement under pile-soil interaction. The paper also discusses the intensity components, plastic and other energy and equivalent viscous damping coefficient cycles occur with varying degrees of degradation of the variation.

Abstract: Soil foundation in Tianjin Harbor is formed by hydraulic filled materials strengthened by vacuum preloading method, which is still with lower strength and larger compressibility. Large settlement and wavy failure of the roads constructed on such soil foundation are often taking place after two or three years of construction, because of the heavy vehicles running on the roads with high frequency. In order to deal with the existing problems of constructing roads on such very soft soil foundation, the following work is carried out: the displacement characteristics of roads constructed on very soft soil foundation are identified; the design methodology of constructing roads is discussed; the settlement of the constructed roads is calculated with FE methods and the mechanism of wavy failure of the roads on very soft soil foundation is analyzed.

Abstract: A process of hydrogen storage in the form of hydrate by utilization of liquefied natural gas(LNG) cold energy was proposed. Hydrogen was recovered from exhaust gas by pressure swing adsorption method, and formed gas hydrate with ice powder under a pressure of 35 MPa and a temperature of 140 K. The process analysis was carried out with partially numerical simulation by Aspen Plus and theoretical calculation. The results show that the energy consumption of hydrogen stored in the hydrate form is 12058 kJ/(kg.H2) and of this hydrogen storage process, the ratio of spent energy to stored energy is 0.10 , which is superior to the most of the other method. The research indicated that if there is cold energy with low temperature available, hydrogen stored in the hydrate form is a method of feasible and energy-efficient.

Abstract: The effect of gas flow rate on degradation of chlorinated phenoxy acetic acids herbicide 2,4-D(2,4-dichlorophenoxyacetic acid) in aqueous solution with O3 or O 3/H 2O2 process was investigated in a bubbling semi-batch reactor. The experiments were conducted to study the degradation rate constant, mass transfer condition, ozone consumption and formation of byproduct hydrogen peroxide at different gas flow rates. The results show that gas flow rate is a complicated parameter in the process. The contact time of gas and liquid phase varies with different gas flow rate, consequently ozone mass transfer condition changes with different gas flow rates. The production rate of ozone, amount of ozone in the end gas and ozone consumption during the degradation with ozonation and O 3/H2O2 process vary with different of gas flow rates. Hydrogen peroxide is a byproduct during the ozonation or O3/H2O2 process of 2,4-D. The production rate of hydrogen peroxide is also affected by the gas flow rate. In general gas flow rate has both positive and negative effect on the 2,4-D degradation.

Abstract: To reduce the water consumption and pollution in car-washing, a combined technique, i.e., electrocoagulation coupled with ultrasound, was proposed to treat the car-washing water for reuse. The effects of parameters (such as current intensity (I), initial pH, electrode distance (d), treatment time (t), and so on) on the removal efficiency of COD and turbidity in the wastewater were studied. The results indicate that the removal efficiency of COD and turbidity is maximum (68.77% and 96.27%, respectively) when I=1.2 A, pH=6.0, d=1.5 cm, and t=20 min. The quality of treated wastewater could meet the COD and turbidity requirements in Water Quality Standard for Urban Water Consumption. Meanwhile, the character of the reaction cell was studied, and it shows that the cell voltage is a linear function of the electrode distance when the current is constant. Compared with the removal rate of pollutants from car-washing wastewater by the single electrocoagulation method, a higher rate could be achieved by this combined technique.

Abstract: This paper is based on permanent magnet synchronous motor Direct Torque Control system as research background. It analyzes the zero voltage vector’s function of regulating electromagnetic torque and provides function relationship curves graph. Based on that, the strategy of 12-sector control based regional interpolation of zero voltage vector is proposed and is applied in the Marine Electric Propulsion System of high-capacity parameters as the operating environment, then is tested. The result shows that the strategy effectively reduces torque ripples as the theoretical analysis. Finally, the application of strategy of regional interpolation is systematically summarized.

Abstract: Divided-period method based on multi-fractal characteristic parameter was proposed to confine the switching times of control devices in the regional power system. Using the fractal theory, we can predict fluctuations of the load and calculate the multi-fractal characteristic parameter of different times. Considering the maximum allowable daily switching times of control devices, the demanded times are classified adaptively using hierarchical clustering method by clustering different times which had the similar multi-fractal characteristic parameter. This method not only reduces the switching times of control devices, but also improves the efficiency of compensation.