直流式低速风洞流动特性研究

针对新建的东北电力大学直流式低速风洞,介绍了其流场品质的测试方法和测试数据分析.包括:实验段风速、气流稳定性、流场均匀性、气流偏角、紊流度等五项,给出了测量的数值结果和相关参数的分布曲线,并确定了风机工作频率与气体流速之间的关系.     

Oxidation behavior of in-situ Al2O3/TiAl composites at 900℃ in static air

In-situ Al2O3/TiAl composites were successfully synthesized from the starting powders of Ti, Al, TiO2 and Nb2O5. The oxidation behavior of the composites at 900℃ in static air was investigated. The results indicate that the composite samples present a much lower oxidation mass gain. Under long-time intensive oxidation exposure, the formed oxide scale is multi-layer. The formation of the outer TiO2 layer is fine and dense, the internal Al2O3 scale has good adhesiveness with the outer TiO2 scale, and the TiO2+Al2O3 mixed layer forming the protective oxide scale is favorable for the improvement of oxidation resistance. It is believed that the incorporation of Al2O3 particulates into the metal matrix decreases the coefficient of thermal expansion of the substrate, and forms a local three-dimensional network structure that can hold the oxide scale. The formation of the oxide scale with fmer particle size, stronger adherence, less micro-defects and slower growth rate can contribute to the improvement of oxidation resistance. Nb element plays an important role in reducing the internal oxidation action of the materials, restraining the growth of TiO2 crystals andpromoting thc stable formation of the Al 2O3-riched layer,which is benfeicial to improve the oxidation properties.     

Aerobic biodegradation of di-n-butyl phthalate by Xiangjiang River sediment and microflora analysis

Di-n-butyl phthalate (DBP), one of phthalate acid esters (PAEs), was investigated to determine its biodegradation rate using Xiangjiang River sediment and find potential DBP degraders in the enrichment culture of the sediment. The sediment sample was incubated with an initial concentration of DBP of 100 mg/L for 5 d. The biodegradation rate of DBP was detected using HPLC and the degraded products were analyzed by GC/MS. Subsequently, the microbial diversity of the enrichment culture was analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results reveal that almost 100% of DBP is degraded after merely 3 d, generating two main degraded products: mono-butyl phthalate (MBP) and 9-octadecenoic acid. After a six-month enrichment period under the pressure of DBP, the dominant family in the final enrichment culture is clustered with the Comamonas sp., the remaining are affiliated with Sphingomonas sp., Hydrogenophaga sp., Rhizobium sp., and Acidovorax sp. The results show the potential of these bacteria to be used in the bioremediation of DBP in the environment.     

Bi-level programming model for reconstruction of urban branch road network

Considering the decision-making variables of the capacities of branch roads and the optimization targets of lowering the saturation of arterial roads and the reconstruction expense of branch roads, the bi-level programming model for reconstructing the branch roads was set up. The upper level model was for determining the enlarged capacities of the branch roads, and the lower level model was for calculating the flows of road sections via the user equilibrium traffic assignment method. The genetic algorithm for solving the bi-level model was designed to obtain the reconstruction capacities of the branch roads. The results show that by the bi-level model and its algorithm, the optimum scheme of urban branch roads reconstruction can be gained, which reduces the saturation of arterial roads apparently, and alleviates traffic congestion. In the data analysis the arterial saturation decreases from 1.100 to 0.996, which verifies the micro-circulation transportation’s function of urban branch road network. Foundation item: Project(2006CB705507) supported by the National Basic Research and Development Program of China; Project(20060533036) supported by the Specialized Research Foundation for the Doctoral Program of Higher Education of China     

Kinetics of nickel leaching from roasting-dissolving residue of spent catalyst with sulfuric acid

Sulfuric acid leaching process was applied to extract nickel from roasting-dissolving residue of a spent catalyst, the effect of different parameters on nickel extraction was investigated by leaching experiments, and the leaching kinetics of nickel was analyzed. The experimental results indicate that the effects of particle size and sulfuric acid concentration on the nickel extraction are remarkable; the effect of reaction temperature is mild; while the effect of stirring speed in the range of 400–1 200 r/min is negligible. Decreasing particle size or increasing sulfuric acid concentration and reaction temperature, the nickel extraction efficiency is improved. 93.5% of nickel in residue is extracted under suitable leaching conditions, including particle size (0.074–0.100) mm, sulfuric acid concentration 30% (mass fraction), temperature 80 °C, reaction time 180 min, mass ratio of liquid to solid 10 and stirring speed 800 r/min. The leaching kinetics analyses shows that the reaction rate of leaching process is controlled by diffusion through the product layer, and the calculated activation energy of 15.8 kJ/mol is characteristic for a diffusion controlled process. Foundation item: Project (50574101) supported by the National Natural Science Foundation of China; Project (2003UDBEA00C020) supported by the Collaborative Project of School and Province of Yunnan Province, China     

Application of cluster analysis to preventive maintenance scheme design of pavement

To quantitatively identify the maintenance demand for each highway segments in the pavement maintenance scheme design,a mathematical model of uniform segment division was established and an approach of applying cluster analysis theory to the uniform segment division and evaluation of pavement maintenance demand was proposed.The actual maintenance project of a highway carried out in Guangdong province was cited as an example to demonstrate the validity of the proposed method.It is proved that the cluster analysis can eliminate human factors in classification without being constrained by the quantities of samples,considering multiple pavement distress indexes and the continuity of samples.Thus it is evident that cluster analysis is an efficient analytical tool in uniform segment division and evaluation of maintenance demand.     

渣油加氢结焦反应条件的研究

使用高压釜反应器,无催化剂条件下,考察了反应温度(410～440 ℃)、初始氢气压力(3.0～7.0 MPa)及停留时间(20～80 min)对渣油加氢结焦及转化率的影响.当温度、停留时间增加时,渣油转化率与结焦率都增大,而初始氢气压力增加时渣油转化率增大,结焦率变化不大.结果表明,反应温度为430 ℃、初始氢气压力为7.0 MPa和反应时间为20 min是现有渣油加氢工艺的最佳反应条件.     

淮水北调输水管道关键技术研究与应用

介绍了输水主管道的设计制造关键技术问题,通过比较备选管材特性,研究了选用的PCCP管道设计制作技术、空气阀布置设计和管道基座安装技术,对管道铺设方案、煤矿塌陷区的地基变形进行了分析。     

四方晶相HfO_2在(100)和(001)方向上光学特性的理论计算

文章采用基于密度泛函理论(DFT)框架下广义梯度近似平面波超软赝势法,计算了四方晶相Hf0_2的电子结构.经带隙校正后,计算了四方晶相Hf0_2在(100)和(001)方向上的光学线性响应函数随光子能量的变化关系,包括复介电函数、复折射率、吸收光谱以及反射光谱.计算结果表明四方晶相Hf0_2在(100)和(001)方向上具有明显的光学各向异性,并且具有从紫外到红外的透明区域.文中计算结果与其它文献报道的计算结果及实验值都吻合较好,由此说明采用密度泛函理论的广义梯度近似来计算HfO_2材料的光学特性是可信的.     

基于精度控制的凸轮反求实践

精度控制是反求实践研究的一项重要内容.论文分析了精度控制的必要性,给出了精度误差的评价标准,通过对打纬共轭凸轮反求实践中各环节的精度控制,有效的控制了反求误差,实现了凸轮的高精度反求,提高了凸轮反求的品质.