Direct numerical simulation of hydrogen turbulent lifted jet flame in a vitiated coflow

The direct numerical simulation (DNS) method with 16 steps detailed chemical kinetics was applied to a lifted turbulent jet flame with H2/N2 fuel issuing into a wide hot coflow of lean combustion products,at temperature of 1045 K and low oxygen concentrations. The chemical reactions were handled by the library function of CHEMKIN which was called by the main program in every time step. Parallel com-putational technology based on message passing interface method (MPI) was used in the simulation. All the cases were run by 12 CPUs on a high performance computer system. Faver-averaged DNS re-sults were obtained by long time averaging the transient profile and compared with the experimental data. The roll-up and evolution of the vortices in jet flame were well captured. The vortices in the same rotating direction attracted each other and those in different rotating directions repulsed each other. Through complex interactions between vortices,the original symmetrical vortex structure could be converted into nonsymmetrical and more complex structures by combination,distortion and splitting of the vortices. The transient profiles of H,OH and H2O mass fraction at 5.76 ms showed the flame structure in jet flame,especially the autoignition regions clearly. The lift-off height was about 9 d―11 d,in agreement with the experimental observation. At the corner point of the flame sheet indicated by OH and H profiles,the combustion was always enhanced by the flame curvature and extended resident time. The profiles of turbulence intensities show that the flames were diffused from the original two outside flame sheets into the core. The DNS results can be considered in developing more accurate and more universal turbulence models.     

Rational construction of NiCo_2O_4@Fe_2O_3 core-shell nanowire arrays for high-performance supercapacitors

Fe_2O_3 electrode materials exhibit excellent electrochemical performance in electrochemical energy storage system. However, its poor electrical conductivity limits its future practical application. The binder-free Ni Co_2O_4@Fe_2O_3 composites was reasonably designed and fabricated on carbon fiber paper with NiCo_2 O_4 nanowires as conductive scaffold in the present investigation. The three-dimensional nanostructure of the porous Fe_2O_3 nanorods coated the Ni Co2 O4 nanowire arrays showed the fascinating electrochemical performance, including high specific capacitance of 262 m F/cm2 at a current density of 1 m A/cm2, and remarkable cycle stability with～74.2% capacitance retention after 4000 cycles. The excellent pseudocapacitance performance of NiCo_2O_4@Fe_2O_3 composite materials is due to synergistic effect between NiCo_2O_4 and Fe_2O_3. The results of the present work show that NiCo_2O_4@Fe_2O_3 core-shell composite electrode is expected to exhibit excellent performance in the field of supercapacitors.     

多片离合器定速滑摩过程摩擦元件间的热量分配系数研究

在多片离合器滑摩过程中,摩擦元件之间的热流分配系数会受厚度和材料特性的影响。建立有限厚摩擦元件的接触传热模型,用有限元耦合计算方法获得了摩擦元件热流分配系数的变化过程,并得到了摩擦元件厚度方向的温度分布。结果表明:热流分配系数在滑摩初期的表面温变时间范围内为定值,但随后会变成另一个稳态常数;半无限厚模型所得的定热流分配系数只在滑摩初始阶段适用,在长时滑摩过程中并不适用,但可用于确定初始热流分配系数。     

工业废弃物和生活垃圾流化床焚烧技术的研究

在废弃物的焚烧特性、床内颗粒流动特性和二次污染物处理等方面系统研究的基础上,综合集成相关技术与设备（如废弃物破碎、烟气处理、渣分离回收、床下点火、热工自动控制等）,形成了系统的异重流化床焚烧新技术,并应用于洗煤泥、煤矸石、污水污泥和城市生活垃圾等的焚烧处理,实践证明,异重流化焚烧技术不失为一种适合中国国情的先进的废弃物焚烧技术。     

余卷积与余代数

在 Ｈｏｍ （ Ａ, Ｃ）中定义余卷积, 其中 Ａ 为代数, Ｃ 为余代数, 由此构作含在 Ｈｏｍ （ Ａ, Ｃ）中的最大余代数． 进一步, 由余卷积构作的余代数和卷积构作的代数一起成为双代数或 Ｈｏｐｆ代数     

动脉中非线性血流的锥度效应

研究了动脉中的锥度对非线性血流的影响,在假定锥度角很小的情况下,应用不可压缩粘性液体的动力学原理建立了一组描述非线性血流的偏微分方程导出了轴向和径向速度分布公式。了锥度角对流场的影响情况。     

Pb（Ⅱ）－Cup络合物导数极谱波研究

在ＰＨ为５～６的ＨＡｃ－六次甲基四胺溶液中，Ｐｂ（Ⅱ）与铜铁试剂产生的络合物在单扫描示波极谱仪上可观察到一灵敏的导数极谱波，其峰电位为－０．６４Ｖ（ＶＳ，ＳＣＥ），峰电流与铅浓度在９．６×１０－８～５．８×１０－６ｍｏｌ·Ｌ－１范围内成线性关系，检测限为１．９×１０－６ｍｏｌ·Ｌ－１，用以测定铅锌矿中铅的结果良好．同时研究了形成铅－铜铁试剂络合物吸附波的条件和性质，并用极谱法测定其络合比为１：１．     

基于动态行为特征加权聚类的加壳恶意软件未知变种检测方法

攻击者为了逃避检测，常利用加壳技术对恶意软件进行加密或压缩，使得安全分析人员以及传统基于静态分析的恶意软件检测方法在恶意软件运行前难以利用反汇编等逆向工具对其进行静态分析。为检测加壳恶意软件，当前主要采用动态分析方法检测加壳恶意软件，然而受限于加壳工具种类和样本规模，以及恶意软件加壳行为带来的混淆噪声，导致传统基于机器学习检测方法存在准确率不足等问题。研究提取并分析加壳恶意软件运行时的系统调用行为特征，识别并筛选出敏感行为，旨在过滤脱壳行为噪声产生的影响；通过对系统调用行为特征加权降维，提升行为特征的有效性；通过对加权降维的行为特征进行聚类分析，最终实现加壳恶意软件未知变种检测和检测模型增量更新。实验结果表明，提出的基于动态行为特征加权聚类的加壳恶意软件未知变种检测方法检测误报率3.9%,相较几种典型机器学习检测方法呈显著降低。     

Straightforward Guess and Determine Analysis Based on Genetic Algorithm

With the development of artificial intelligence, the genetic algorithm has been widely used in many fields. In cryptography, the authors find it is natural to code an individual and design its fitness in a genetic algorithm for a straightforward guess and determine analysis (SGDA, in short). Based on this observation, the authors propose an SGDA based on genetic algorithm. Comparing it with the other three SGDAs based on exhaustive search, MILP method and CPP method respectively, the authors illustrate its effectiveness by three stream ciphers: Small scale SNOW 2.0, medium scale Enocoro-128v2 and large scale Trivium. The results show our method is significantly superior to them, especially for Trivium, the method can find a solution of 165 variables in less than one hour, while the other three methods are not applicable due to its enormous search space of size 2^619.37. As far as we know, it is a best solution in an SGDA for Trivium so far.

     

淀粉/聚乙烯薄膜中聚乙烯的降解特性研究

对含３０％淀粉的淀粉／聚乙烯薄膜进行环境降解、环境生物降解和环境曝晒试验,发现淀粉／聚乙烯薄膜在环境中暴晒降解的速度远远大于生物降解的速度,在应用环境中经过４周的降解,薄膜中聚乙烯的分子量损失达６２．５％;经５周的曝晒降解后,薄膜中聚乙炮的分子量损失达８７．５％;薄膜降解后,平板流变粘度降低２个数量级以上。