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     

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。     

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.     

基于四阶累积量的波束域MUSIC方法

在非白噪声背景下,基于二阶统计量的高分辨方法性能较差.基于四阶累积量的高分辨方法能较好地抑制空间高斯噪声,但其运算量较大.为了解决这一矛盾,文章提出了一种基于四阶累积量的波束域MUSIC方法.仿真分析和实验结果表明,与阵元域四阶累积量MUSIC方法相比,论文所提方法降低了分辨门限,减小了估计偏差和均方根误差,同时减小了运算量.     

水果蔬菜中有机磷农药残留的快速检测技术研究

利用有机磷杀虫剂敌百虫属酯类化合物在碱性条件下易水解成醇类、酚类和磷酸的性质,将水解产物醇类、酚类与具氧化性的KMnO4有色液反应使溶液的颜色发生改变,根据试液颜色的改变程度与敌百虫量的关系制成标准比色卡,用色卡法快速检测水果蔬菜中有机磷农药残留量。研究表明,该方法对敌百虫的检测灵敏度为0．058mg／kg,单个样品全过程检测只需5min,具有检测时间短、成本低、简单方便、快捷等特点,适用一般家庭或农贸市场、超市快速检测水果、蔬菜中有机磷农药残留量。