The hydrodynamic forces and flow field of artificial reef models in steady flow were numerically investigated using the RNG k–εturbulent model.The numerical simulation results are consistent with results observed by experimental means.A comparative study indicates that the corresponding errors of forces between calculated values and values observed in the experiment vary in the range of 2.3%–11.2%and that the corresponding errors of velocities vary in the range of 1.3%–15.8%. The flow field numerical results show that upstream and vortices exist when the current passes over and through the surface of the reef model.This study suggests that the numerical simulation method can be applied to predict the forces and flow field associated with artificial reefs.
A microbial consortium named Y4 capable of producing biopolymers was isolated from petroleum-contaminated soil in the Dagang Oilfield,China.It includes four bacterial strains:Y4-1 (Paenibacillus sp.),Y4-2(Actinomadura sp.),Y4-3(Uncultured bacterium clone)and Y4-4(Brevibacillus sp.).The optimal conditions for the growth of the consortium Y4 were as follows:temperature about 46°C, pH about 7.0 and salinity about 20.0 g/L.The major metabolites were analyzed with gas chromatography-mass spectrometry(GC-MS).A comparison was made between individual strains and the microbial consortium for biopolymer production in different treatment processes.The experimental results showed that the microbial consortium Y4 could produce more biopolymers than individual strains,and the reason might be attributed to the synergetic action of strains.The biopolymers were observed with optical and electron microscopes and analyzed by paper chromatography.It was found that the biopolymers produced by the microbial consortium Y4 were insoluble in water and were of reticular structure,and it was concluded that the biopolymers were cellulose.Through a series of simulation experiments with sand cores,it was found that the microbial consortium Y4 could reduce the permeability of reservoir beds,and improve the efficiency of water flooding by growing biomass and producing biopolymers. The oil recovery was enhanced by 3.5%on average.The results indicated that the consortium Y4 could be used in microbial enhanced oil recovery and play an important role in bioremediation of oil polluted environments.
Wang Jing Yan Guiwen An Mingquan Liu Jieli Zhang Houming Chen Yun
We investigated nerve growth factor precursor (proNGF) and mature NGF expression in ischemic and non-ischemic cortices after cerebral ischemia-reperfusion injury. In both ischemic and non-ischemic cortices, proNGF was found to be present in the extracellular space and cytoplasm. In addition, mature NGF was expressed in extracellular space, but with a very low signal. In ischemic cortex only, proNGF was significantly decreased, reaching a minimal level at 1 day. Mature NGF was increased at 4 hours, then reached a minimal level at 3 days. The p75 neurotrophin receptor (p75NTR) was significantly decreased after ischemia, and increased at 3 days after ischemia. These results confirmed that proNGF was the predominant form of NGF during the pathological process of cerebral ischemia-reperfusion injury. In addition, our findings suggest that ischemic injury may influence the conversion of proNGF to mature NGF, and that proNGF/p75NTR may be involved in reperfusion injury.
Guoqian HeJian GuoJiachuan DuanWenming XuNing ChenHongxia LiLi He
Three-dimensionally ordered macro-porous(3DOM) TiO2 and ceria-modified 3DOM TiO2 supported platinum catalysts were prepared with template and impregnation methods,and the resultant samples were characterized by scanning electron microscopy(SEM) ,X-ray diffractometer(XRD) ,high-resolution transmission electron microscopy(HRTEM) and temperature programmed reduction(TPR) techniques. The catalytic performances over the platinum-based catalysts were investigated for water-gas shift(WGS) reaction in a wide temperature range(180-360 °C) . The results showed that 3DOM Pt/TiO2 catalyst exhibited obviously better catalytic performance than the corresponding non macro-porous catalyst,owing to the macro-porous structure favoring mass transfer. Addition of ceria into 3DOM Pt/TiO2 led to improvement of catalytic activity. TPR and HRTEM results showed that the interaction existed between ceria and titanium oxide and addition of ceria promoted the reducibility of platinum oxide and TiO2 on the interface of platinum and TiO2 particles,which contributed to high activity of the ceria modified catalysts. The results indicated that ceria-modified 3DOM Pt/TiO2 was a promising candidate of fuel cell oriented WGS catalyst.
The membrane fouling characteristics of high concentration powdered activated carbon-microfiltration (HCPAC-MF) integrated process are studied by comparing them with those of direct microfitration system using the particle counter,scanning electron microscope (SEM) and atomic force microscope (AFM). The results indicate that the specific flux of HCPAC-MF is 3 times better than that of the direct filtration process after the system is stabilized. The addition of HCPAC changes the particle distribution of raw water and influences the structure of surface fouling layer. The PAC with irregular shapes aggregating on the membrane surface makes the cake layer structure loose and increases the roughness of membrane surface,and this decreases the thickness of hydrodynamic boundary layer and the membrane resistance. After the physical cleaning,the membrane surface and pores are clean without any fouling matters aggregation,which illustrates that the cake layer of PAC can be formed quickly in this HCPAC environment and prevent the occurrence of irreversible fouling.
A model free intelligent multivariable fuzzy controller (MFC) designed for modulating the vapor compression cycles in a residential inverter-driven air conditioning is proposed. The novel controller combines a traditional fuzzy controller (TFC) and an additional coupling fuzzy controller,the coupling fuzzy controller is introduced to compensate for the unknown cross-coupling effects of this multivariable system. In order to evaluate the control performance of the MFC,it is digitally implemented in terms of regulating the desired evaporating temperature and superheat. The experimental results show the effectiveness of the MFC for improvement of system performance and energy efficiency.
Based on the size of network and the number of paths in the network,we proposed a model of topology complexity of a network to measure the topology complexity of the network. Based on the analyses of the effects of the number of the equipment,the types of equipment and the processing time of the node on the complexity of the network with the equipment-constrained,a complexity model of equipment-constrained network was constructed to measure the integrated complexity of the equipment-constrained network. The algorithms for the two models were also developed. An automatic generator of the random single label network was developed to test the models. The results show that the models can correctly evaluate the topology complexity and the integrated complexity of the networks.
Catalytic properties of MnOx -FeOx complex oxide (hereafter denoted as Mn-Fe) catalysts modified with different loadings of chromium oxide were investigated by using the combination of physico-chemical techniques, such as N2 physisorption, X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), in situ Fourier transform infrared spectroscopy (in situ FT-IR) and temperature-programmed reduction (TPR) and their catalytic activities were evaluated with the selective catalytic reduction (SCR) of NOx by NH3 . It was found that with the addition of Cr, more NO could be removed in the low-temperature window (below 120℃). Among the tested catalysts, Mn-Fe-Cr (2 : 2 : 1) catalyst exhibited the best catalytic performance at 80℃ with the NO conversion higher than 90%. The combination of the reaction and characterization results indicated that (1) the strong interaction among tertiary metal oxides existed in the catalysts when Cr was appropriately added, which made the active components better dispersed with less agglomeration and sintering and the largest BET specific surface area could be obtained; (2) Cr improved the low-temperature reducibility of the catalyst and promoted the formation of the active intermediate (-NH+3 ), which favored the low-temperature SCR reaction.
Kai ShenYaping ZhangXiaolei WangHaitao XuKeqin SunChangcheng Zhou
