Effects of fuel droplet size on soot formation in spray flames formed in a laminar counterflow

The effects of fuel droplet size on soot formation in spray flames formed in a laminar counterflow are investigated experimentally and numerically. Sauter mean diameter (SMD) of quasi-monodispersed fuel spray (n-decane) is carefully controlled independently from the other spray characteristics using a frequency-tunable vibratory orifice atomizer, and the two-dimensional spatial distributions of soot volume fraction and soot particle size are measured by laser induced incandescence (LII) and time resolved LII (TIRE-LII), respectively. In addition, the soot formation processes are examined in detail by a two-dimensional direct numerical simulation (DNS) employing a kinetically based soot model with flamelet model. The results show that the soot formation area and location are strongly affected by the SMD of the fuel spray. As the SMD of the fuel spray increases, the average soot formation area expands, whereas local suppression of soot formation is instantaneously observed in the spray flames because of the appearance of groups of unburned droplets. The size of soot particles tend to be larger in the outer part of the soot formation area compared to soot in the inner part. This is because the surface growth of soot particles markedly proceeds compared to the coagulation and oxidation.     

Effect of alloying elements on hydrogen environment embrittlement of AISI type 304 austenitic stainless steel

The chemical composition of an AISI type 304 austenitic stainless was systematically modified in order to evaluate the influence of the elements Mo, Ni, Si, S, Cr and Mn on the material’s susceptibility to hydrogen environment embrittlement (HEE). Mechanical properties were evaluated by tensile testing at room temperature in air at ambient pressure and in a 40 MPa hydrogen gas atmosphere. For every chemical composition, the corresponding austenite stability was evaluated by magnetic response measurements and thermodynamic calculations based on the Calphad method. Tensile test results show that yield and tensile strength are negligibly affected by the presence of hydrogen, whereas measurements of elongation to rupture and reduction of area indicate an increasing ductility loss with decreasing austenite stability. Concerning modifications of alloy composition, an increase in Si, Mn and Cr content showed a significant improvement of material’s ductility compared to other alloying elements.     

抗HICX65管线钢带的开发

采用低碳、低锰、低磷、超低硫及添加适量合金元素的成分设计,配合严格的钢水脱硫、脱磷等冶炼工艺以及合理的控轧控冷工艺,济钢开发了具有针状铁素体组织的抗HICX65管线钢带。由于成品钢带组织中铁素体晶粒细小均匀、横断面上无明显硬相条带组织以及M／A所占比例较小,而且弥散度高,开发出的X65钢带具有良好的力学性能、很好的抗动态撕裂性能、优异的抗HIC性能。     

Continuous production of flexible carbon nanotube-based transparent conductive films

This work shows a simple, single-stage, scalable method for the continuous production of high-quality carbon nanotube-polymer transparent conductive films from carbon feedstock. Besides the ease of scalability, a particular advantage of this process is that the concentration of nanotubes in the films, and thus transparency and conductivity, can be adjusted by changing simple process parameters. Therefore, films can be readily prepared for any application desired, ranging from solar cells to flat panel displays. Our best results show a surface resistivity of the order of 300 Ω square^-1 for a film with 80% transparency, which is promising at this early stage of process development.     

Si含量对纳米晶Fe_(87-x)Cu_1Nb_3Si_xB_9合金磁性能的影响

研究了Si含量对Fe87-xCu1Nb3SixB9合金经不同方式退火后磁性能的影响。结果表明:随Si含量的增加,Fe87-xCu1Nb3SixB9合金经普通退火后软磁性能逐渐得到优化;经磁退火后可感生出单轴磁各向异性,且磁退火特征随Si含量的增加而逐渐明显。根据横磁退火实验结果计算出的感生磁各向异性值Ku,则由26.7J/m3(Si=9.5at%)降低至14.1J/m3(Si=13.5at%)。由实验数据的分析认为Fe87-xCu1Nb3SixB9合金在高Si含量时经普通退火或纵磁退火后呈现优异的软磁特性,归因于析出的α-Fe(Si)相晶粒具有小的磁晶各向异性K1,从而导致合金具有更低的有效磁各向异性常数K所至。     

夹杂物对X120管线钢氢致开裂的影响

研究了X120管线实验钢的抗H_2S氢致裂纹敏感性。用多功能金相显微镜对X120管线实验钢非金属夹杂物进行颗粒度分析,用场发射扫描电子显微镜(SEM)及能谱仪(EDS)观察和分析裂纹形貌和裂纹内夹杂物。结果表明:X120管线实验钢氢致开裂一般都从非金属夹杂物处萌生扩展,并互相交叉连接;实验钢中B类夹杂物较D类夹杂物易于形成长条型裂纹,且B类夹杂物级别越高,其HIC敏感性越大;X120管线钢中S、Al含量越高,其夹杂物级别越高,非金属夹杂物数量越多,氢致开裂敏感性也越大。     

Analysis of the FIC detector data at the n_TOF facility

Fission cross-section measurements with the Fast Ionization Chamber (FIC) at the CERN n_TOF facility were challenged by intense signals due to γ-rays and ultra-relativistic particles from the impact of the 20 GeV proton pulses on the neutron spallation target. A method for analyzing the data taken with Flash Analog to Digital Converters (FADC) was developed to treat these problems in an automated way to provide a reliable background subtraction and a fit routine for identifying fission events even at high energies. The analysis is illustrated at the example of the fission cross-section of ²³⁸U relative to that of ²³⁵U in the energy range from 40 keV to 300 MeV.     

Radiation hardness of polysiloxane scintillators analyzed by ion beam induced luminescence

The radiation hardness of polysiloxane based scintillators has been measured by ion beam induced luminescence (IBIL). The light intensity as a function of the irradiation fluence with an He⁺ beam at 1.8 MeV (1.0 μA/cm²) has been measured on undoped polymers synthesized with different amounts of phenyl units and on polysiloxanes doped with two different dye molecules (BBOT and Lumogen Violet) sensitizing the scintillation yield.     

Point by Point model calculation of the prompt neutron multiplicity distribution P(ν) for spontaneous and neutron induced fission of actinides

The prompt neutron multiplicity distribution P(ν) is a very sensitive quantity which depends on the model calculation of the multi-parametric matrix ν(A,TKE) and on the fission fragment distributions.     

榆林地区地质环境特征与地质灾害的关系

本文阐述了榆林市地质环境特征与地质灾害分布特征的关系, 本区主要地质灾害有滑坡、泥石流、地面塌陷等, 地质灾害的诱发因素可分为自然因素和人为因素, 其中人为因素对地质灾害的发生发展影响很大。针对这些现象, 提出了地质灾害的防治措施, 以促进地质环境与经济建设的和谐发展。