Advanced Materials Research Vols. 347-353

Abstract: The problem of noise in power transformer was pay attention to by this paper. The paper presents the design methodology for the active noise control (ANC) of sound disturbances in power transformer. The active noise attenuation algorithm uses the framework of output-error based optimization of a linearly parameterized filter for feedforward sound compensation to select optimal location of sensor and demonstrate the effectiveness of active noise attention in a large power transformer. The ANC controller can automatically measure the sound disturbances and select the compensate parameters to realize the noise cancellation. With 220kV power transformer noise cancellation, for example, the simulating results prove that the ANC technology to cancel the noise in power transformer is an effective way.

Abstract: The Sn4+-doped nano-TiO2 particles with various amounts of dopant Sn4+ irons was prepared by sol-gel method using tetrabutyl titanate(TEOT) as one of the primary raw materials at different calcination temperatures (400-700°C). The products were characterized by XRD and SEM, which revealed that the crystal structure of Sn4+-doped nano-TiO2 changes from anatase to rutile with the calcination temperature increasing, and the nanoparticles diameter was around 10-30 nm. The photocatalytic degradation of ammonia nitrogen in aquaculture wastewater was investigated by using Sn4+-doped nano-TiO2 under UV irradiation. The experimental results can be stated as follows: when the ratio of dopant Sn4+ was 3% wt, the calcination temperature of Sn4+-doped nano-TiO2 was 500 °C, the dosage of Sn4+-doped nano-TiO2 was 0.8 g/L, respectively, if the reaction time may last 4h, the removal rate of ammonia-N was expected to reach 87.13%.

Abstract: A new method of determinating doxycycline residues in milks and content in serum,table and injection samples was established with Self-ordered ring fluorescence microscopic imaging technique. In the presence of hexahydropyridine and poly (vinyl alcohol)-124, Zn²⁺-doxycycline (DC) system can form a SOR on the hydrophobic glass slides surfaces based on the capillary effect. The maximum fluorescent intensity (I_max) at central ring belt was found to be proportional to DC content. when the droplet volume is 0.5μL, the present SOR method can be used to determine DC in a range of 4.54×10^-15–6.81×10^-13 mol•ring^-1, and the limit of detection (LOD) with a threefold signal to noise ratio (S/N = 3) was 4.54×10^-15 mol•ring^-1 (2.17×10^-8 mol•L^-1). With the present method, the residues in milks and content in serum, tablet and injection samples were satisfactorily detected with recoveries of 96.3-102.0% and RSD of 1.4-2.2%, respectively, indicating that the method is reliable and practical.

Abstract: Six specific types of surface dusts were collected from different e-waste disposal areas in Shanghai, China for the determination of toxic metals including Zn, Pb, Ni, Cd, Cr and Cu. These samples were obtained from interior of home appliance, second-hand household appliance maintaining store, open manual dissembling yard, enclosed electronic waste warehouse, enclosed dissembling workshop, as well as outside yard of plant. ICP-AES analyzing results revealed that metal concentrations in dust from home appliance interior and second-hand household appliance maintaining store were obviously higher than the soil background values. And the metal concentrations of dusts from open manual dissembling yard were similar to enclosed electronic waste warehouse. The concentrations of Pb, Zn and Cu in dust from enclosed dissembling workshop were about 3646.10, 3485.23 and 4049.70 mg/kg, which were respectively 9, 19 and 45 times higher than outside yard of plant. The potential ecological risks of metal pollution in these dusts were analyzed by estimating the distribution characterization of samples and the heavy metals. The results showed that potential ecological risk of Cu was the highest, and then was the Cd, Cr was the least. The ecological risk indexes of metals in dusts from enclosed dissembling workshop, home appliance interior and second-hand household appliance maintained store were considered to be significantly healthy harm, while those from open manual dissembling yard and enclosed electronic waste warehouse were relatively less harm.

Abstract: The municipal solid waste (MSW) generation rate is being accelerated in China. Problems encountered in waste management are particularly serious in small and medium-sized towns. Pulandian as a typical medium-sized town in China is investigated in the paper. The daily amount of MSW generated in urban district of Pulandian in 2008 was 0.95 kg/capita, which is comparable to that of some big city in China. Characteristics analysis on MSW was also carried out. The current status of MSW collection, recycling and transportation was introduced and the problems were identified. The MSW treatment and disposal in Pulandian has caused serious contamination. The new MSW treatment plant using integrated disposal technology and transport centre for reduction and recycling of MSW under construction is preferred.

Abstract: The main objective of the study is to explore how ultrasonic work with ultraviolet, in an attempt to find out the synergistic effect in controlling the phenomenon of microbial photoreactivation, as well as to analyse the feasibility of synergistic disinfection and related theories. Two different frequencies of ultrasonic transducers (28/40kHz)were used in combination with ultraviolet for secondary effluent disinfection. By controlling the process parameters that may contribute to the efficiency of synergistic disinfection, such as different reaction time, respective ultrasonic and ultraviolet dose. The results show that the synergistic disinfection of ultrasonic and ultraviolet can inhibit such a phenomenon, while maintaining continuous disinfection ability of ultraviolet. Ultrasonic has great potential in enhancing continuous sterilization abilities of ultraviolet. Synergistic disinfection has great advantages compared with other disinfection technologies and has a promising prospect in future use.

Abstract: The reaeration performance in smooth and parallel flashboard spillways with 3cm, 6cm and 9cm board space over curve dams has been experimentally investigated respectively. Reaeration efficiencies of different types of spillways, in particular the effects of varying discharge rate of overflow and drop-water depth have been taken account in detail. The test data illustrates that the reaeration efficiency increases with increasing drop-water depth, and decreases with increasing discharge current; the flashboard spillways appear to offer markedly higher reaeration efficiency than the smooth spillway, which increases gradually with reduction of the space between streamwise adjacent flashboards. Empirical correlations predicting spill Froude number Fdo, relative weir depth hw/h and reaeration efficiency of different types of spillways on curve dams are developed. The results indicate that flashboard spillways are effective for oxygen transfer.

Abstract: In order to maintain the stable operation of grid system, the grid company requires wind turbine generator system with low-voltage ride through (LVRT) capability. With this issue, the article builds a double-fed wind turbine generator system model, Crowbar circuit strategy model to protect rotor-side inverter and fault pitch control strategy model to inhibition rotor speed during grid fault. Then all the models and strategies are verified by the simulation of grid low voltage. The simulation results show that these models can complete LVRT.

Abstract: This paper introduces the household wind turbine and grid joint power supply system, indicates the outstanding advantages of the system: energy saving, environmental protection, security and so on. And the economic model is established, based on the wind speed information of Shanghai, to analyze the economic development potential.

Abstract: There are many tropical forest resources in Xishuangbanna area; it is a very important status in China. But because a large number of rubber plantations are expanding as far as possible and the areas of urban construction land are increasing, the areas of tropical forest are decreasing rapidly, which lead to serious fragmentation. In the paper, we choose the typical area of Xishuangbanna area as the research area to study the vegetation change trajectory using ETM and SPOT images acquired on different time. On the base of data pretreatment, two aspects researches were carried out. On the one hand, spectral information and NDVI information of each type of vegetation were analyzed to classify the ETM and SPOT images using the method of decision tree respectively. By classification post-processing, we could get the ways of the vegetation type conversion. On the other hand, ETM and SPOT PAN Images were integrated by the PCA to acquire the information of vegetation change including vegetation gain or loss. Finally, comprehensive information on two aspects of the vegetation changes was analyzed to acquire the vegetation change trajectory from 2000 to 2007 in the Xishuangbannan area. The result showed vegetation conversions that changed from one type to another type were frequent. A larger proportion of other type vegetation was transformed to rubber plantations.