生物促生剂强化膜生物反应器处理印染废水的研究

通过向膜生物反应器（MBR）添加生物促生剂后形成生物促生剂膜生物反应器,分析生物促生剂对活性污泥性能以及对印染废水处理效果的影响,试验结果表明添加生物促生剂后,活性污泥结构紧密,颗粒增大,且微型动物的种类增多,同时COD和氨氮的处理效果分别提高了5％和8％左右,染料的去除率也提高了6％,适当延长水力停留时间或者泥龄可有效提高色度的去除效果。说明添加生物促生剂能较好的改善污泥性能,提高系统处理效果。     

以磷腈为稳定剂的次氯酸钠消毒液

论述了次氯酸钠消毒液的稳定机理,探讨了以六氯环三磷腈为稳定剂的稳定机理以及实验方法。     

米曲霉CPA毒素的5-氟色氨酸分子探针研究

米曲霉中往往含有完整的环匹阿尼酸(cyclopiazonic acid,CPA)毒素生物合成基因簇.鉴于CPAs对食品安全的潜在威胁和其不同的存在形式,依据CPA的生物合成机制推测可将外源氟代前体探针化合物嵌入CPA生物合成途径,从而形成氟代物用于靶向检测.结果 显示,米曲霉CPA合成途径可以接受5-F-L-Trp为底...     

BROADBAND ROTOR NOISE PREDICTION BASED ON A NEW FREQUENCY-DOMAIN FOUMULATION

This article studies the broadband noise of a rotor in upstream turbulence. A numerical approach is proposed, based on frequency domain, for predicting rotor broadband noise which requires the aerodynamic sources to be integrated over the actual blade surface rather than over the mean-chord surface. The prediction of the radiated rotor broadband noise due to turbulence is made. This method is validated through a comparison between numerical predictions and measured data, with a reasonable agreement. Noise level directivity shows that the main lobe is located along the rotor axis, while the minimum noise occurs in the direction vertical to the rotor axis.     

FLOW-PIPE-SEEPAGE COUPLING ANALYSIS OF SPANNING INITIATION OF A PARTIALLY-EMBEDDED PIPELINE

The initiation of pipeline spanning involves the coupling between the flow over the pipeline and the seepage-flow in the soil underneath the pipeline. The pipeline spanning initiation is experimentally observed and discussed in this article. It is qualitatively indicated that the pressure-drop induced soil seepage failure is the predominant cause for pipeline spanning initiation. A flow-pipe-seepage sequential coupling Finite Element Method (FEM) model is proposed to simulate the coupling between the water flow-field and the soil seepage-field. A critical hydraulic gradient is obtained for oblique seepage failure of the sand in the direction tangent to the pipe. Parametric study is performed to investigate the effects of inflow velocity, pipe embedment on the pressure-drop, and the effects of soil internal friction angle and pipe embedment-to-diameter ratio on the critical flow velocity for pipeline spanning initiation. It is indicated that the dimensionless critical flow velocity changes approximately linearly with the soil internal friction angle for the submarine pipeline partially-embedded in a sandy seabed.     

机载激光雷达技术在电力选线工程中的应用

 介绍了机载激光雷达技术及传统电力选线的方法,阐述了机载激光雷达技术在电力选线工程中的具体应用优势,主要体现在线路及立杆点的优化设计、需要砍伐树木的面积估算、房屋拆迁数量估算、树木及房屋高度测量、实时断面量测等方面。介绍了机载激光雷达技术在安徽省电力线路设计项目中的应用,相关的数据处理,以及基于ArcGIS用VB语言开发的真三维电力选线测图系统。野外测量表明,应用该系统选线能够满足电力选线的精度要求。最后客观总结了该技术的优缺点,同时指出该技术在未来具有的应用前景。     

地下水污染曝气修复技术进展

从曝气流型和组分反应传质两方面总结了地下水污染曝气修复技术的研究进展,提出已有研究在地下水流及土壤介质特性与曝气流型相互影响、脉冲曝气机理、曝气-抽提技术联用研究、生物降解作用等方面存在的问题,并探讨该技术未来可能的研究方向,指出该技术在技术改良、工程优化设计及机理研究三方面存在深入研究的空间,为进一步研究和应用推广提供参考依据。     

Direct numerical and large eddy simulation of longitudinal flow along triangular array of rods using the lattice Boltzmann method

Results of direct numerical (DNS) and large eddy simulation (LES) of turbulent longitudinal flow in rod bundles are presented using the lattice Boltzmann method with the Bhatnagar–Gross–Krook collision operator [P.L. Bhatnagar, E.P. Gross, M. Krook, A model for collision processes in gases. I. Small amplitude processes in charged and neutral one-component systems, Phys. Rev. 94 (1954) 511; Y.H. Qian, d’Humiéres, P. Lallemand, Lattice BGK models for Navier-Stokes equation, Europhys. Lett. 17 (1992) 479] as a computational framework. The problem requires the accurate modeling of curved walls, to which the method proposed by Yu et al. [D. Yu, M.R. Luo, W. Shyy, Viscous flow computations with the method of lattice Boltzmann equation, Prog. Aerospace Sci. 39 (2003) 329] has been applied. The computational domain is a regular hexagonal prism around the rod. Opposite sides of the prism are coupled periodically. In the longitudinal direction periodical boundary conditions are applied and the flow is driven by a body force. Simulations were carried out using two three-dimensional lattices. It has been found that the application of the model with 19 velocities (D3Q19) gives qualitatively false result. However, we have found that the application of the model with 27 links (D3Q27) can provide the proper mean axial velocity profile, and it also predicts the secondary flow patterns deduced from measurements [A.C. Trupp, R.S. Azad, The structure of turbulent flow in triangular array rod bundles, Nucl. Eng. Des. 32 (1975) 47]. Flow pulsation phenomenon is also observed in our simulations just like in some recent measurements of Krauss and Meyer [T. Krauss, L. Meyer, Experimental investigation of turbulent transport of momentum and energy in heated rod bundle, Nucl. Eng. Des. 180 (1998) 185].     

Effect of the slurry composition on the piezoelectric properties of PZT ceramics fabricated via materials extrusion 3D printing

Herein, the effect of the binder content in lead zirconate titanate (PZT) slurry has been systematically studied to improve the piezoelectric properties of PZT ceramics prepared via material extrusion 3D printing. For smooth printing, a slurry with a binder concentration ranging from 6 to 12 wt% was proposed. The porosity of the green body first decreased and then increased with an increase in the binder concentration, and the minimum porosity was obtained when the binder concentration reached 10 wt%. Samples with increased density were obtained after debinding and lead-rich atmosphere sintering. PZT piezoceramics fabricated using a binder content of 10 wt% exhibit the maximum relative density (96.9%), largest piezoelectric constant (342.6 pC/N) and dielectric constant (1621). Based on the above process, the wood pile structure and helical twentytetrahedral structural components were successfully fabricated using the material extrusion process. This research lays the foundation for the engineering application of 3D printing to fabricate high-performance piezoceramics with complex shapes.     

Study on thermal shock resistance of Sc2O3 and Y2O3 co-stabilized ZrO2 thermal barrier coatings

In order to reveal the effect of Sc₂O₃ and Y₂O₃ co-doping system on the thermal shock resistance of ZrO₂ thermal barrier coatings, Y₂O₃ stabilized ZrO₂ thermal barrier coatings (YSZ TBCs) and Sc₂O₃–Y₂O₃ co-stabilized ZrO₂ thermal barrier coatings (ScYSZ TBCs) were prepared by atmospheric plasma spraying technology. The surface and cross-section micromorphologies of YSZ ceramic coating and ScYSZ ceramic coatings were compared, and their phase composition before and after heat treatment at 1200 °C was analyzed. Whereupon, the thermal shock experiment of the two TBCs at 1100 °C was carried out. The results show that the micromorphologies of YSZ ceramic coating and ScYSZ ceramic coating were not much different, but the porosity of the latter was slightly higher. Before heat treatment, the phase composition of both YSZ ceramic coating and ScYSZ ceramic coating was a single T′ phase. After heat treatment, the phase composition of YSZ ceramic coating was a mixture of M phase, T phase, and C phase, while that of ScYSZ ceramic coating was still a single T′ phase, indicating ScYSZ ceramic coating had better T′ phase stability, which could be attributed to the co-doping system of Sc₂O₃ and Y₂O₃ facilitated the formation of defect clusters. In the thermal shock experiment, the thermal shock life of YSZ TBCs was 310 times, while that of ScYSZ TBCs was 370 times, indicating the latter had better thermal shock resistance. The difference in thermal shock resistance could be attributed to the different sintering resistance of ceramic coatings and the different growth rates of thermally grown oxide in the two TBCs. Furthermore, the thermal shock failure modes of YSZ TBCs and ScYSZ TBCs were different, the former was delamination, while the latter was delamination and shallow spallation.